robert_e_bone
There are a couple of freeware soft synths that have some pretty good sounds.
 
There are a couple of drawbacks though - please note that even with the couple of drawbacks, I still chose to use them until literally just yesterday.
 
PLEASE NOTE -both the MinimoogVA and the ARP2600VA are 32-bit, so they must either be used in a 32-bit Sonar, or with BitBridge/JBridge in a 64-bit Sonar.
 
They do have great sounds, though, and since they are free, I recommend you take a look at them - download and listen.  They both work well with ASIO from your interface, so the sound quality is good, on top of which they are really good free creations of a Minimoog and an ARP200.
 
I JUST literally purchased the Arturia V Collection - which is an INCREDIBLE collection of 64-bit classic synths - 9 synths and 30 drum machines - It was on sale for $199 for all of these, and the regular price is back up to its normal $399 - here is the link to what is included, in case you want to look at these someday, particularly if they go on sale again: 
 
http://www.arturia.com/evolution/en/products/v-collection/details.html
 
Here are links to the MinimogueVA and the ARP2600VA, which you can get now for free:
 
MinimogueVA:  http://home.no/gunnare/downloads.htm
 
ARP2600VA: http://glenstegner.com/softsynths.html
 
By the way, if you ever pick up a synth called FM 8. from Native Instruments, either by itself or as part of one of their Komplete bundles, send me a Private Message with your email address, and I will cheerfully send you LITERALLY tens of thousands of presets for FM 8, that represent LITERALLY every single factory sound EVER released by Yamaha for any of the DX-type synths, such as DX7, DX8, DX100, DX1, DX5, DX21, GS1, GS2, TX-series, etc.
 
These sounds are amazing enough on their own, but unlike the limitations the originals had, you can add all kinds of effects to each sound, resulting in lush, authentic digital pianos, and all of those unique sounds.  I posted a thread some months ago, offering to email all of the DX presets to whoever wanted them, and I did end up sending them all to 6-7 different folks.
 
Also, Native Instruments offers a couple of free synths - they call them 'Players', including a great-sounding "taster" synth that allow you to play a  small number of representative sounds from their flagship Kontakt synth.  They hope you love the sound quality enough to purchase the real Kontakt, which IS the gold standard Sampler.  
 
The other one 'plays' a representative number of presets from another incredible synth of theirs, Reaktor 5.  That synth allows you to assemble synths from 'building block components' of all of the different kinds of synthesis out there, so you can combine FM, additive, subtractive, etc types of synths, into a brand new kind of synth.  
 
There are thousands of free synths that folks have built with this synth 'factory'.
 
Here are links to these two free synthesizers, Kontakt 5 Player and Reaktor 5 Player:
 
Kontakt 5 Player: http://www.native-instruments.com/en/products/komplete/synths-samplers/kontakt-5-player/free-download/
 
Reaktor 5 Player: http://www.native-instruments.com/en/products/komplete/synths-samplers/reaktor-5-player/
 
I hope you enjoy the free stuff.  The other Sonar-included synths may grow on you, in time, as well.
 
Bob Bone
 

+1 on what Robert posted.  The MinimougueVa and ARP2600VA are free and have pretty good classic prog type sounds.  While not part of Sonar itself, they work well with bitbridge.  You certainly should add them to your collection.
 

I happen to use Z3ta+ 2.1 for old "moog" type sounds (using vintage wave shapes - the default start-up patch is a good example). They seem to be good for both the top end and the bottom.
 
regards
Dave
X3d Producer on Windows 7/64.

Thank you very much for all your comments, all very interesting and helpful.

FYI - When I reviewed Rapture many years ago, I posted an online example of a Rapture 4-pole LP filter sweep and the same from Arturia's Minimoog emulation. No one could tell the difference.
 
Remember, these are synthesizers...you can make them do pretty much anything you want. Give me something with more than one sawtooth oscillator and a 4-pole filter, and I can probably make it sound like a Minimoog   Also remember part of the Minimoog "sound" involved the envelopes, which had distinctive shapes quite different from today's common rate/level envelopes.

> I posted an online example of a Rapture 4-pole LP filter sweep and the same from Arturia's Minimoog emulation
 
Hmmm maybe it's time to try that test again with these synths, Monark and the real instrument? :).
 
I agree though, a lot of virtual synths are (basically) the same, it's the way the UI is handled, and how it is initially calibrated is what makes the synth for me. Some synths are unique though like FM.
 
For me Z3TA+2 is a great virtual synth to start with (and it's generally cheap).

CakeAlexS
> I posted an online example of a Rapture 4-pole LP filter sweep and the same from Arturia's Minimoog emulation
 
Hmmm maybe it's time to try that test again with these synths, Monark and the real instrument? :).
 
I agree though, a lot of virtual synths are (basically) the same, it's the way the UI is handled, and how it is initially calibrated is what makes the synth for me. Some synths are unique though like FM.

I thought it fair to compare virtual instrument to virtual instrument. I actually liked Creamware's "Minimoog" better in some ways, but it sounded less like a hardware Minimoog (I have one, signed by Bob Moog when he came over to visit ).
 
But what everyone seems to forget is that no listener has ever said "I was going to buy your CD, but...that wasn't a real Minimoog, it was a software emulation."

One of the ultimate VST's for analog synthesis is this:
 
http://www.sonicprojects.ch/opxpro2/description.html
 
It is an Oberheim clone and I mean this thing is serious.  Firstly I am a bit of an Oberheim fan having owned many of them going back to OBX and OBXa and OB8 Matrix 12 and all that.  I really know how Oberheims sound. This VST is the most amazing recreation of the Oberheim sound I have ever heard.  It is stunning to say the least. It is also modelled on the original SEM filters too.
 
I realise too that it is something you have to buy but it is a killer analog sounding VST.  You can always get OPX too which is cheaper but sztill amazing and upgrade later. The upgrade is worth it though.

What Jeff has here is a perfect example. In my view there are many synths capable of these sort of sounds and sound just as good. Morark may sound better IMHO, however the demos's are pretty impressive.
 
The point is moot however, what makes a synth is:
 
1) Good presets.
2) A UI the user likes and is comfortable with.
3) A UI that allows great sounds to be created quickly.
4) Maybe something they are already familiar with.
 
So this Oberheim clone ticks all the right boxes.
 
Most people tend to look at 1 rather than 3 more, many only use presets which in my view should be a crime.
 
There are lots of opinions out there, but really all people are banging on about is when to add the milk to their tea (that's if they add milk at all). They all (more or less) sound the same nowadays, with a few notable exceptions.

I have a Micromoog and a Voyager, and I still use plugins all the time. I currently have a KingKorg VA on demo and for laughs I put it next to my Micro and tried to copy my basic saw bass sound. The sweet spots were in different places but  I got close enough to use them interchangeably in the same bassline with noone the wiser.
 
I will never get rid of any of my analogs, they each have their charm and do some tricks software can't, but for most general purpose sounds software VAs are so good these days that most of the time it's not worth firing up the vintage stuff and waiting half an hour until it stays moderately in tune.
 
Some great free stuff has been posted here. I'm glad to see Jeff also endorsing OPX-II Pro, for the paid stuff. It's where I'd turn for the next step if I were you.

CakeAlexS
many only use presets which in my view should be a crime.
 

This is a common view, for which I have some sympathy.

However, in the seventies, Tony Banks used an ARP ProSoloist for that classic Genesis sound.

It was a preset synth.

I also have a 150 year old Grand Piano that only has one preset sound.