Maybe I was a bit naive (or in this case 32 bit naive)...  All I had learned a few years back was that maybe 64 bit was a little better sound quality but that there were few plugs available for it, so I always opted to stay in the 32 bit realm.  I have an ADK computer that has always been pretty stable and it seems that for the most part any crashes were cause by heavy mixing/editing for hours without saving (my own fault).  So I started looking into adding additional RAM to my system and someone mentioned that it won't make my performance any better to that end if I am running in 32 bit.  I was like huh??   Apparently 32 bit can only take advantage of 2 gigs of ram MAX at any given point in time so even if you have 8 or 16 gigs on your system you are only using 2.   So, with this upgrade I said that's it.... I am going 64 bit.  and so far all is well though I have not tracked any new projects in it yet.  I like X3 and the new features are pretty cool.  I can't wait to dig in further.
 
On the one hand, jumping to 64 bit sucks because there are so many plugs I have purchased that now don't show up and can't be used.  The one I know is going to cause me grief is Drumagog 5 as they do not have a 64 bit version for PC.  That has been my safety net when tracking live drums....  That other assorted eq's, comps,  etc....  I can do without.  I have learned that once ya understand how compressors work and what they do.... you can work with any one compressor if you had to and get the job done, even at that... X3 producer gives ya a bunch of options there too.    I am not sure how the new melodyne thing works yet... is that one track only per project?  One track that you have to work with outside the project?   What gives there?
 
My only other issue is that I can't get sonar to see my new faderport.  I have tried the common fixes for this including running the Admin mode regsvr32 thing and telling it where the dll file is... still nothing.  I can tell ya that presonuses support dept blows! Every time I have had to deal with them I find myself frustrated beyond belief.   they take forever with email support and you could spend a day on hold for phone support.  I am getting off topic. Sorry! 
 
I just wanted to drop a line and see how others have coped with the 64 bit world?    I never knew that I wasn't utilizing my computers abilities.  That was an eye opener for me.
 
 

Oops, double post -- see below.

ChuckC
....
On the one hand, jumping to 64 bit sucks because there are so many plugs I have purchased that now don't show up and can't be used.  The one I know is going to cause me grief is Drumagog 5 as they do not have a 64 bit version for PC.....

First, you need to check with all of the manufacturers of your 32-bit plugs.  Many offer a 64-bit version, you just need to find it in the download area of their website (Or you might have to request it.  Point is, if it's available, you as a registered user are typically entitled to either version).
 
Secondly, for those plugs that are 32-bit only, and "don't show up" in your 64 bit Sonar, my guess is you don't have them set up correctly so that Sonar can scan and Bitbridge them (automatically "bridge" 32 bit to 64-bit).  Easiest way to do this is to create a dedicated folder and put only your 32 bit VST plugs in there.  IOW, have one folder for 64 bit plugs, and another for 32 bit.
 
Go to VST settings, and add the location of the newly created 32 bit plugin folder.   Press OK, then do a Reset and rescan.
 
That should do it!
 
FWIW, I have half a dozen 32 bit VSTs in their own folder working just fine in 64 bit Sonar.  

There was a cheap little bridge app called "JBridge" that was useful for covering any 32-bit plugins that Sonar's built in bridge couldn't quite handle.  I recall I had to use this for just a couple of plugs, the rest Sonar handled fine on its own.
 
Luckily most plugins nowadays have 64-bit versions.  The biggest benefit for me was something you mentioned, that is vastly increased addressable memory space.  That's a godsend if you use a lot of sample-based stuff. 

32 bit is limited to 4 Gb, not 2 Gb, but after you factor in the OS and any other background programs, you end up with around 512 - 1024 Mb being constantly in use for those, so only 3 Gb left for everything else.

4 Gb is todays minimum spec for computers, especially with the latest OSes reserving up to 1 Gb, any less means that barely nothing is going to run. Also with ram prices being as cheap as they are, there's little excuse to not have 8-16 Gb anyway, and of youre on the PC, Microsofts last two OSes were cheapo on pre order upgrades anyway, so there's little reason to not have already gotten Win 7 or 8 64 bit. Vista did indeed suck, but I'm glad I bought it now because it got me windows 7 and 8 professional editions for very little through the upgrade offers.

I'm still using 12 Gb ram with an X58 setup. Still don't need anymore, and I cant get larger capacity modules that are as good as my 2 Gb performance ones.

JonD- I will Check to see how my VST's are set up.  So you are saying that if they are all in one folder, that I should create a 2nd one named say "32bit VSTs" and move all 32 bit plugs to it?
 
Lilloyd- I will check into Jbridge.  Thanks!
 
Vab- If I had the specs 2 gig/4gig wrong.... I apologize.  I am not sure what you were getting at in your 2nd paragraph as I am running Windows 7 home in 64 bit.   And (I am being honest here) your last sentence may as well have been in Chinese... cause ya completely lost me there!   

The main advantage of a 64-bit Windows is more memory available to programs that can use it, and it may provide some improvement in processing speed depending on the application. There is no benefit whatsoever to sound quality if the math is done on a 64 bit OS or a 32 bit OS. Sonar can do its internal math to 64 bit precision on a 32 bit system.

Chuck, the Melodyne Essential with x3 can handle more tracks; it is just that it is for monophonic tracks like vocals. The full Melodyne can work with polyphonic tracks.

I made the change on X1 and have not even installed 32 Bit on the X2 or X3 upgrades. I don't use many plug ins that are not 64 Bit these days either.

ChuckC,
 
If you right click on TaskBar bottom of Win 7 Screen.
Then click "Start Task Manager", you can monitor your memory use
along with you Apps being used.  Extra tool to use.