Currently my computer has 2 sound cards:
 
1) M-Audio Delta-44 (with OMNI I/O box) - for Sonar only
2) ASUS Xonar DX - for everything else (games, listening to music, etc.)
 
I have 2 cards because the Xonar has high latency and fewer inputs, which makes it bad for Sonar... but the Delta-44 is not ideal for gaming (I think because of lack of certain sample rates or onboard processing).
 
I've been using this setup for the past 5 years or so, and am getting increasingly annoyed at the following issues:
 
1) I need to switch headphones each time I want to use Sonar.  The pair I have attached to the Delta-44 sound different from the ones I have attached to the Xonar, so when I listen to my songs on the Xonar, they don't sound as good as they did in Sonar.
 
2) The Delta-44's OMNI I/O box uses US power, and since I'm in New Zealand, I need to run a converter for it.  This ends up wasting power, which turns into higher power bills.  Not the end of the world, but annoying. 
 
3) The Delta-44 is picking up noise from either my power supply or video card (or something else in the computer); the Xonar is not.
 
4) The Xonar has an annoying UI (when switching between headphones and surround sound speakers) and poor ASIO behavior.  It hasn't had new drivers in years, so I have lost hope on it getting "fixed".
 
So now I'm thinking about getting a single audio card to replace the Delta-44 and Xonar.

Here are the requirements:
 
Must-haves:
1) low latency
2) low noise
3) ability to record at 16 bit / 44.1 KHz
4) good for gaming  (whatever that requires)
5) headphone port on front of computer or breakout box (not at the back of the computer)
 
Would be nice:  (but not required)
6) 2 pairs of stereo inputs [4 mono inputs]
7) surround sound output
8) 1 or 2 MIDI in/out pairs
9) ability to record at 24 bit / 96 KHz
 
For those of you who use a single card for both Sonar and gaming/movies, do you have any recommendations?

Seems most modern CPU's come with very respectable on board audio thats meets your need for gaming. 
But on board audio will never work with Sonar. 
SO just purchase a external audio interface that has the features you need and only use that for working with a DAW. If you need surround your not going to find that easily in an audio interface. 
Many have multiple outputs but I doubt if they can be used by WIndows for gaming. 
 
Most Sonar users simply swicth to on board for Windows apps and use the external audio interface for DAW. You just need to replace your outdated interface. 

I use a Tascam for DAW stuff and the onboard audio for everything else.  I have each of their outputs piped to a Samson C-Control matrix.  Simple to enable/disable/switch between the inputs and the outputs for different sets of speakers/monitors/sub.  I HATE unplugging/re-plugging and such, so the $99 was well worth it for me.
 
 

The reason I got the Xonar (instead of onboard audio) is it has a front mount (for easy headphone/mic access).  Do onboard audio cards these days have front mounts?
 
Of course, onboard audio is probably a moot point for this computer since I'm not going to change the motherboard.

In my scenario, it doesn't matter about the access as much because once connected, the C-Control is where speakers and phones get plugged in.

To answer you question. No, audio interfaces are almost all external now. 
They sit on your desktop so it's not a problem with getting at the controls and headphone jacks. 
 
I use only my audio interface. It works for everything , Sonar, Wave Lab, Win Amp, Media player and anything streamed off the internet. 
 
This totaly aviods all the hassles you are having as I only need the one device, one set of speakers and sub and one set of phones. 
I'm not a gamer but I would imagine the sound quailty would be top notch for that too, I have a sub and I could patch in as many powered speakers as I dare. I have my PA system set up so I can check out my backing tracks in the system they will be played through. 
 
You say your Delta doesn't support some audio formats, another good reason to upgrade. Most all these days will support all standard formats and then some. 

Thanks for the info!  I read a little about the Focusrite.  It's not that expensive, and seems to have good latency.
 
So, is USB the way to go these days, rather than PCI?  (When I bought the Delta more than 10 years ago, USB was considered too slow for an audio interface).

 i upgraded to a Focusrite firewire Pro 24 from a Delta 1010LT years ago.  Prob the best decision I ever made for my sound.  You'll love the interface in a convenient location and not having to crawl behind the computer to change connections.  Someday I will move from firewire as it seems to have been made obsolete by thunderbolt.  Some USB interfaces use USB 3 which has more bandwidth but supposedly USB 2 is sufficient for music.  I run my sound output thru a Mackie Big Knob which give you more sound routing options.  Most pro music interfaces won't give you a 7.1 surround... you'll have to settle for 2.1, at least from my knowledge, but i have no reason to use surround so I may be wrong about that issue. 

I used a collection of cheap USB and some onboard audio until 7 years ago when I shelled out $400 for a Focusrite Saffire Pro 40 (Firewire, 8 input preamps and lots of other I/O). My computer MoBo has digital I/O and I also run that via optical I/O thru the Saffire for grabbing audio off web streaming and CD/DVDs. 
 
Save your $$ and just get something good...the Pro 40 (above) is still on market, now for $499...these things don't go obsolete like computers. Good audio is Good audio. 
 
If I had to replace it, I would probably go with USB, but at the time, USB3 was not available. The Firewire with a high end i7 processor is all you need...Focusrite and Tascam seem to be the hot brands in the mid-range price bracket at the moment and for most of the last decade. 

Firewire is external, right?  No need to install anything inside the case?
 
I've heard very good things about Focusrite.
 
I don't record a lot of audio; 2 mono inputs is probably fine for me.  And a stereo output (to my powered speakers).  1 headphone jack is a must; 2 would be ideal. 
 
Most of what I do is soft synths.  So, having low latency when playing Kontakt (or Dimension Pro) is key.  To keep latency under 10ms (or, ideally, under 5ms), do you think I should focus (no pun intended) on USB, firewire, PCI, or PCI-E (assuming I have any of those slots left)?