Pci-e Gpu?!?
let me get this right, you have an AsRock P4VM800, but you also have an XFX 7600GT?
this is strange, because the 7600GT is on PCI-Express and that mobo has AGP 8x
also, in games having 2GB of RAM is today standard (and also recommended), so the best hunch is to upgrade your mobo, CPU and GPU (which I think is a 7600GS, far slower than the GT)
Recommendations:
mobo -> AsRock 775DUAL-VSTA (cheap, supports Intel Core 2 Duo, AGP x8, PCI-E x4, SATA, DDR2 & DDR1) that sells for about 50$
CPU -> Core 2 Duo E6400 (or E6300) sells for about 255$ (or 190$ for E6300)
GPU -> XFX 7600GT Fatal1ty Edition or (if you have the money) a 7950GT;this will set you back for 180$ or 320$
RAM -> keep it, it should work with this mobo, thus 0$
note: due to the x4 of the PCI-E of this board you will get a 5-8% performance handicap for your GPU