Re: Graphics upgrade concerns...
I'd get a used G92 8800GT if you could find one, they have good deals on them nowadays (like $75).
If you want a new card, I'd go with an ATI 4850 or 4870, depending which one you can find a better "deal" on. Yea it probably won't run at its best, but you can probably find a 4870 for $150 and it would still be good for a future rig too.
1. Q6600 @ 3.2, ASUS P5Q Pro Turbo, Powercolor HD 4890 CrossFire, 4GB Mushkin DDR2-1066, 3x 24" LCD, Matrox TripleHead2Go, Audigy 2 ZS
2. Q9550 @ 3.7, ASUS P5K, Galaxy 8800GT G92, 2GB Mushkin DDR2-1066, Samsung 710N + Samsung 205BW, Audigy 2 + SB Live! 5.1 (hooked up together, really), dad's comp
3. XP-M 2500+ @ 205x11.5, Gigabyte nForce2-400, GeForce4 Ti4200, 2x512MB OCZ DDR-400 "Premier", oldie