New CPU or new gpu

okay, I finally got a new monitor, with full hd resolution. Only problem is that the full hd resoultion is too much for my currnet hardware, and I have suffered considerable slow-downs in Sins of a Solar Empire. I have been considering getting a radeon 4870 or gtx260, but I only have a amd 5000+ dual core. Should I upgrade the graphics card or the proc to a phenom II 720?

Currnet graphics card is a 9600 gt.

9600GT should max out SOASE easily :shock:

so upgrade my cpu then?

thanks

and games like crysis require a good cpu and a good gpu, and even the best computers still struggle with it and other games like empire total war at high res...