You guys are trying to think like logical, sane people. This is a customer with 2G to spend.
Also get him some half decent graphics, 9800 pro's at 190-200$ CDN are becoming a steal, far more reliable than the cheap XFX 6600GT's up here and their name sounds better, more "pro". The 9800pro has a 60$ price gap between the 6600GT.
Go with a full gig of ram, if their's one thing he's going to notice, it's extra ram.
Also go with RAID 1 with 2 200 gig seagate drives, your customer will be VERY pleased with the reliability and speed of these drives, you can keep the OS on a seperate 40 IDE drive if wanted.
Also remeber, nice monitor, non intergrated sound (cheap card) nice keyboard and mouse
This gets you some extra $$$ and a happy customer