I just installed X3 on my Dell Opti 330, with Windows 7 and an old Audigy 2 ZS card, which worked fine in my old home-brew computer but records with lots of distortion in this Opt 330.
 
I decided to go the audio interface route, and it looks like the Focusrite Scarlett 2i2 will fit the bill.
 
However, I'm wondering how midi is handled. Sometimes I work with midi for starters (take piano, for example), and then output the midi to a soft synth. Dumb question, but it is correct to assume that I would use the Audigy 2 ZS for midi, and would be able to output it to the Focusrite Scarlett 2i2? In other words, I'm concerned about actually being able to hear the midi.
 
Obviously I'm a little naïve about the subject and I'd appreciate any help. Thanks!
 
OptiPlex 330
Audigy 2 ZS
Sonar X3 c
Windows 7

Focusrite has nice drivers, but I am not familiar with the Scarlett 2i2 specifically. Are you using a MIDI controller in your intended setup?

Because you mention the Creative series I will assume you might have been using it's Sound Fonts? correct?
You are much better off using Sonars Soft synths which are all internal and will playback without external midi. 
But if you are planning on recording your own midi keyboard controller, it will have to have USB output. The Scarlett does not have standard MIDI ports. IF your MIDI controller does not have USB output then you should buy an interface with MIDI ports. 

Focusrite one you mention does not have MIDI connections, but you can get one that does.
http://www.sweetwater.com/store/detail/AudioBoxUSB/
 
one of many that do have MIDI connections and not an endorsement of any such audio/interface.
http://www.sweetwater.com/c695--USB_Audio_Interfaces
 
http://www.sweetwater.com/store/detail/DuoCaptureEX/
 
Hundred more for a Focusrite that does have MIDI in and out also.
Some do and some do not have MIDI connections.
 
 

Thanks guys.
 
For some reason my brain was locked into a false idea that I had to use soundfonts in a midi track first, and then output it to a virtual instrument once that was done. Duuuhhhh.... obviously I can input directly to the VI.
 
It sounds like the Focusrite unit will work out just fine. Sorry for my dumb presupposition.

Or you could go out and buy a dedicated one or two input midi interface. They aren't expensive and will play well with the 2i2.