CPU and GPU combo - enough power?

Hi,

I have a friend who's thinking of a minimum upgrade before a complete overhaul next year in Q2.

Specs:

Intel Pentium 4 541 3.20Ghz 800Mhz FSB
Mobo Gigabyte GA-8I915p Duo
1GB DDR2 533Mhz
PSU 430w

Please point out what I have missed out on.

What would be the best GPU that a comp with these specs can handle? E.g. ATI Radeon 5670 or ATI Radeon 4350?

Also, I understand the most advanced CPU the motherboard can handle is the Intel Pentium 4. Please correct me if I am wrong. I'm wondering if it can handle core 2 duos, etc.

Regards

Thanks in advance