need advice for pc upgrade

To begin with, I only want to change my graphic card(or add 1) and maybe change my power supply.

I got a NVIDIA 7900 GT, pretty good card but i need better performance(Elder scroll is quite a juicy game).

So I was wondering if i should dual it or buy something better.I got a budget that comes around 1300$.

thanks for your help. and sorry if that message seems confusing, being french and all makes things hard...

i will upgrade and assemble another pc and im sure that ill be getting Core 2 Duo E6600 as the processor and im still undecided on the motherboard and most especially the video card..

pls help us..:oops: