dpotseluev
Not identical memory modules not good for stability. Now good performance for audio recording is 8gb or 16gb RAM. Processor - need more cores and MHz for realtime FX support. Video card not get much more performance for sound recording, only for software interface. General - processor.

Pretty straightforward- thanks, Dan! So going for a more powerful CPU (6 cores @ 3.1Ghz) will certainly be a good upgrade against my current system (4 cores @ 2.6Ghz).
I'm going to buy another RAM stick to balance out to 8gb - looking at my usage, I rarely, if ever, go over about 5gb, so spending up on 16gb for a machine from 2009 probably wouldn't be worth my while.
I'll hold off on the graphics card for a while. I won't be doing much gaming or graphics-work in he near future anyway!

Gonna just close this topic up - I picked up the unit today. Ran over to a local computer hardare store and grabbed a couple of 1394 cables... had some trouble getting the unit recognized in Win7 before I realized the port was disabled in the BIOS. After that, it worked a treat! very clean preamps, simple to use, great very low-latency drivers and all! Overall I'm very satisfied with this purchase... $100 got me a unit 4 times greater than what I had before... and I paid the same amount! 
 
Haha! Sorry to make a big deal about what is essentially legacy-hardware. But I'm satisfied to the max! 

Have fun.