My son is in the IT field and pretty knowledgeable about computers in general.  I asked him to configure a system for me because he gets good deals on Lenovo through work.  The system he came up with for the price I gave him seems pretty robust but it has only Realtek Integrated Audio.  I know from past experience that no matter how fast a computer is the audio processing is a different animal and requires special hardware.  Is that still the case?  If I move ahead with the purchase am I better off with an internal sound card or an external interface?  I use Sonar for MIDI (driving a Korg Kronos 88, a Roland XV-5050 and occasionally a soft synth) and to record and produce a lot of MP3 files.  If an internal sound card is still a good way to go, does anyone have a recommendation?  Is SoundBlaster Recon 3D any good?  How about ZXR?  If an external interface is the way to go, what should I look for, given that I typically use only one or two MIDI devices and limited vocal recording?

You definitely want to use a dedicated audio interface.

• Fidelity
• Stability (when working with DAW software)
• Low latency performance

Soundblaster units are fine for gaming... but sub-par for recording/mixing audio.
 
External units generally have lower noise-floor.
If the A/D D/A converters are inside the box, it's hard to get the noise-floor below -100dB.
Good external units have a noise-floor of -107dB or better.  
The best units have a noise-floor of ~-117dB (these are more expensive).
 
 

Generally, the internal soundcards (i.e. Realtek, Soundblaster, etc...) aren't suited at all for pro audio recording/mixing/producing and would probably "choke" when attempting to do this. You would definitely need an external interface and there's a lot to choose from.....
 
For around $150, I recommend checking out the Focusrite 2i4 as they have excellent driver support and are rock solid in performance. A lot of Sonarites also use Focusrite products and looking at what your needs are, the 2i4 seems to fit you really well.
 
(BTW, no I don't work for Focusrite .....just a very happy customer)
 
Specifications

• 2 in / 4 out USB audio interface
• 96 KHz, 24-bit conversion
• 2 Focusrite microphone preamplifiers
• Red anodised aluminium unibody chassis

Front panel

• 2 line/mic/instrument combination inputs - high quality XLR/ ¼ “ TRS Jack Combo
• 2 line/inst switches
• 2 illuminating “PAD” buttons
• 2 Gain knobs
• 2 Gain halo signal indicators
• 48V Phantom power switch
• MIDI activity LED indicator
• USB connection LED indicator
• “DIRECT MONITOR” control
• “STEREO/MONO” switch for direct monitor
• Large monitor level dial (controls headphone and line level outputs)
• Headphone output - ¼” TRS Jack
• Headphone level knob
• “HEADPHONE SOURCE” switch

Rear panel

• 2 balanced monitor outputs – TRS (channels 1-2)
• 4 unbalanced outputs – RCA Phono (channels 1-4)
• MIDI IO
• USB 2.0 Port
• Kensington Lock slot

 

Audio for computers is not that hard to do unless there is a problem or the speed of the computer is slower than what you can really do with the computer.
 
http://www.thesycon.de/deu/latency_check.shtml
 
Setting up the computer for music may take some tweaking of the OS, downing automatic functions and tasks that can be done manually, and preserving your audio takes (or MIDI) on the computer - maintenance of the computer.
 
There are many audio/interfaces but drivers are very important with the device and have the correct connections to record or make music on the computer whereas soundcards do not have proper connections except in the form of 3.5mm plug-ins for line inputs or outputs and generally never any MIDI connections on those soundcards.
 
Although there are many places on-line and off-line (like a music store or GC maybe) reading will be required to rifle through all the Options that can be had in buying equipment for such an endeavor.
http://www.sweetwater.com/shop/computer-audio/audio_interfaces/
 
That searching for that equipment on the Internet or in the music store will be up to you.
Reviews and generally opinions from other people who have bought said equipment for the purpose will be your opinion whether it is designed for what you need and how you will use the equipment.
 
 And as you can see there are pages of equipment and not all may be even listed at one website.
http://www.sweetwater.com/c695--USB_Audio_Interfaces
or whatever type you choose to run on the computer.
 

You do want to use an audio interface.
But make a list of the options YOU need. Example above recommendation of th 2i4 would not work at all for me because I need SPDIF. I also don't like bus power as I have had issues in the past with that. So make a list of the options you need for now and the future and shop around. 
 
Most interfaces in the same price range will have the same basic features but sometimes you need just the right combo. Like front panel controls, Say one interfaces is missing a simple thing like separate mix control for headphones. Now you have to go buy another piece of equipment to do this.
Some interfaces include DSP so you can have effects while tracking. 
 
Make a wish list and look at the spec sheets 
 

just as important (IMHO) is the quality of the mic preamplifiers. Some entry level units like the ones discussed here have better sounding mic preamps than others. Midi or not, its likely that at some point you will want to record something with a mic. 

As others have said, a dedicated interface is a good idea. That said, a ZXR will work if you wish to use it. Creative has competent ASIO drivers in my experience. However I'd get a Focusrite unit instead. Personally I use an Auzentch HTHD, which has a Creative X-Fi chip on it, for Windows sound and gaming, and a Focusrite Scarlett 6i6 for pro audio. I find it nicer to have two seperate interfaces.

Nice post, JohnnyV.  :)
 
Bob Bone