need lots of help deciding what to do with this pc
i dont know much about hardware and im worried im not getting the best experience with games.
amd athlon 64 x2 4200+
ATI Radeon HD 3870 X2
the mother board is Asus M3A32-MVP Deluxe (2 PCI, 4 PCI-E x16, 4 DDR2 DIMM, Audio, Gigabit LAN, IEEE-1394)
i just wanna know if any components are holding it back and if i can make any improvements for a couple hundred dollars(minus the money i would get for selling the old parts).