Well if thats your budget for CPU.. then this comes in under budget
$279.99 you can easily overclock it to 3ghz too
and boy it will laugh in the face of a P4, P4 doesnt even come close.
Newegg.com - Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache LGA 775 Processor - Retail
if you can wait till january.. it should be much cheaper as Intel releasing the rest of their New cpu's.
Believe me dude.. i know people have budgets and they can only afford whats in their price range. but putting $100 extra to a better component REALLY MAKES A DIFFERENCE. I.e. your a hardcore gamer.. you dont want to be battling lag, low quality, low rez.. it all leads to frustration. So if you spend a little more and get the better parts, you not only have a faster pc youll LIVE LONGER!
thats how i see it.
Deffo get the Quad Q6600 G0
Nvidia 8800GT or Ati 3870XT
Samsung 22" LCD monitor
other parts are pretty much standard
P35 or 680 mobo
2GB DDR2 Ballistix Ram
Brand name 500watt+ Powersupply
If your a gamer, youll be well impressed with your quad with say a 8800GT with it