Hi Pollock
I have two networked PCs, one which is purely for business (XP, MS Office, Photoshop, Pinnacle, Spyware, emails etc), the other is my 'Boy's Toys Machine'.
The second PC has two accounts, one purely for AH and FB, the second for Music Production. Each account uses different soundcards (I have two installed ), and has different processes running.
Both machines have the usual NAV and Firewalls (which are resource heavy), but by keeping the other particularly 'heavy' applications separate (particularly MS-Office), the performance of both machines is much better. I also removed Norton Internet Security 2004 (which is a real resource hog) and reinstalled Norton System Works 2003 (updated) which although still quite heavy, is much less of a burden on the system
The business machine is an ASUS P4B266, Intel P4 1.8c Northwood, 512 Ram - perfectly quick enough for MS-Office and Photography stuff. The Boys Toys machine is an ASUS P4C800, Intel P4 2.6c Northwood, 1 gig Ram, SB Audigy 2ZS (for games), EgoSys WamiRack (for Music), ATI 9800XT. This machine runs through a Dell 2001FP 20inch LCD (16ms response) limited to 60Fps and rarely drops below 30Fps in AH at 1600x1200x32 with the sliders about one third from the left hand side.
Hope this helps