Hey i gt a p4, g31 board, 2.66 ghz. i need to upgrade my graphics card.

Well to be honest any low to mid range card like the 9600 GSO (rebranded 8800 GS) will be bottlenecked by that Pentium 4 regardless, but if you really cannot upgrade your CPU, the 9600 GSO would be OK. This depends on your budget though, you can get a BFG GeForce 9800 GT for $79.99 off newegg which should perform pretty decently.

The 9800GT won't be able to run at its maximum potential paired with a Pentium 4.

Yeah I know, even something like a S939 Athlon 64 X2 3800+, which I would think would beat a Pentium 4, bottlenecks an HD 4670. I'm just thinking the best card for around $80 would be the 9800 GT, I'm just supposing the OP is on a somewhat tight budget considering he does not want to upgrade his CPU, which may be too costly.

get that 9600GSO like Lmeow said above, no need spend more money for your PC, better save money to build a new whole system...  

What do you have already? Perhaps you need the CPU more then the GPU.

G31 chipset = socket 775, 2.66ghz P4's for 775 - no such thing, Core 2 (E67xx perhaps), maybe Pentium D 805 (2.66ghz) - post back with PROPER specs

G31 = entry level chipset/mobo's of the time = entry level PSU aswell - another thing to check - what brand and model?

Also how much ram do you have?

i got a p4 2.66 with 2gb ddr2 running on a foxconn radeon xpress 200 integrated graphics motherboard with 17" monitor. i am also looking for a decent graphics upgrade. While i can spend on a graphics card, i don't plan upgrade the system for now as most of my work is done well on the system

which will be a good graphics card to buy to run games at 1440x900 resolution on my machine which is not going to be bottlenecked by the cpu!! i haven't been gaming since 2004 and have a lot of catching up to do.  

You're going to struggle at that res with a Pentium 4, I can promise you.

what abt 1280x1024. i was thinking about a 9600gt. will it be a overkill with my cpu and should i instead opt for a 4650?

What is your motherboard? AGP? PCI? PCIE?

You would be good with 9600GT(PCIE) or HD4650(AGP), yes, your cpu will bottlenecking that card, but at least you'll see a better performance than your previous onboard graphic...

i have PCI-E slot. got a great deal on a slightly used 8800gt and picked it up.   came at under $70.
in my country 9800gt is still at $150 and 6600gt at $120. thanks for all your inputs.