I don't see a massive difference between sound cards, but I suppose if I was editing a lot I would.
The problem that jumped out at me is that your FSB is 333MHz and your memory is DDR400. Your DDR will slow down to accomodate your FSB speed. If you are not planning to overclock your FSB to 400 then I suggest you get a faster CPU or slower memory.
I would personally go for slower memory, get yourself some 512 Mb (2 x 256 Mb) Corsair TwinX, DDR, PC2700LLPT, Low Latency memory.
512 Mb Corsair XMS, DDR, PC3200PT, Cas 3. If you only want to take up 1 DIMM slot.
I also think you should get a SATA hard drive.
[size=0.5]Full Aluminium ThermalTake Case
AMD Athlon XP 3200+ *400 FSB* Barton (2.2GHz)
ThermalTake Volcano 11+ Xaser Edition Air Cooling
1024MB Corsair TwinX XMS 3200 (Dual Channel 2x512) 2-3-2-6
256Mb XFX 7800 GS EXTREME
2x WD Raptors (10krpm 8MB Cache) 36.7GB using RAID -0
Video Logic SonicXplosion 5.1 Soundcard[/size]