Graphics card upgrade??

[dayn0]

my system;
intel e6550 2.3Ghz
gigabyte GA-P35-S3 mobo
kingston twin 1gb hyper x 1066Mhz (i currently also have corsair 2GB twin 5300 installed also but can easily be removed)
gigabyte 512MB 8500GT

i was wanting to upgrade to ither gigabyte 1GB HD4850 or gigabyte 9800GTX+. i would like to know which is better and weather it is even worthwile to upgrade to this? i am concidering oc my cpu.

 

[customisbetter]

If you overclock to 2.8-9 Ghz and get one of those cards you will see an Enormous improvement in frames. Ingact, Games will actually run with either of those cards. How have you been using an 8500 GT?

 

[dayn0]

well i havnt realy had a choice havnt had enough money untill now. oh and i ment is it worthwile with my system to uprgade to somthing that good. will i c the benifits??

also can i oc to 2.8-9Ghz with stock heatsink im not realy sure how to remove/install a new one. and anyone know a good guide to overclock with my cpu and mobo. im guesing ill have to adjust the FSB cause ive read that the maultiplier is fixed in most intel C2D