hi i am just receving a computer from my dads work and i wand to mod it

it has no graphis card
it has a pentium 4 2.66ghz
and 256 ram

and i am wanting to upgrade to (i have price spyed the prices)
AMD ATHLON 64 3500+ SKT939- $534.38

GALAXY NVIDIA 7800GT 256MB DDR3 DVI - VIVO - PCI EXPRESS $567.90
or
Sapphire ATI Radeon X800 GTO (ULTIMATE) 256MB DDR3 PCI-Express$450.00

Mushkin Extreme Performance REDLINE 1GB (2x512MB) DDR500 CL2-2-2 @ 3.3V $381.55(dual chanel i think)

Asus A8N SLI skt939 Motherboard- $175.47

Prices are in nzd

tell me if i need anything else and if i dont need the processor and if not caould you recomend a new mother board because it dont have pci-e

oh and buy the way it is a ibm net vista that is about two years old