A few questions about RAM and a CPU

[Greeny]

Hi there,

Some of you may remember a good while ago i posted a list of parts for a new comp i was going to build, well i still havent built it, and while i get the final bits of money together just thought i'd get a few questions answered..

so first..

Which is better

A) 3.0Ghz Prescott with 1MB L2 Cache
OR
B) 3.0Ghz Northwood with 512kb Cache

I know one has a higher cache but i've heard the prescott doesnt perform as well, so which is better? - say to run on a Asus P4C800-E Deluxe

and secondly, if i buy 1Gb of DDR400 (2x512MB) which is a websites own brand will it perform just as well as say some Kingston or Corsair? (bearing in mind i dont want to overclock)

Hopefully i will build the comp in a few months time.. (PS is so close )

Thanks..

EDIT: Also, which do you guys think is better, a 6800 GT or X800 Pro? bearing in mind i dont want to mod it or whatever...