New comp config

Guys my sister wants to buy new computer so i was thinking that some of you guys might be a specialist better than myself:D

Pentium+GeForce or AMD+Radeon?
What cards and proc's should i choose in both configs?
(and why)

i got about 1000$ for the PC only without monitor,keyboard, mouse and DVD.

I do know a lot about getting a good config or at least judge one.1000$ is a lot here.You can get at least 1terabyte of hd memory 4gb of ram,buy 2x ati cards (preferably to be of newer generations(they are better but also break faster too).Procesor perhaps i7 XD.Make a list and i'll see if it's okay.

what you have posted will cost 2k$ or more in here

was thinking about i5 500gb HD 2 or 4gb ram dunno bout the card yet, but the mainboard will be SLI compatible for sure

i dunno a lot bout stuff like that but i can try to give you a advice

get the ati one its better then nvidia
if u can get the quad procesor
windovs xp black edition
and memory from 320gb to 1 terabyt