Tell your friend to get whatever he wants. it is his money, CPU in the 2GHz or 2000+ and more are more than sufficient. CPU is not all, A top of the line CPU coupled with poor video card, memory or mobo will perform badly compared to an medium range CPU (2.4 or 2500+) that is matched with good and fast components.
So, imho, thell him to first check for a good video card if his is not up to date and after, just check for mobo/cpu/ram . A well balanced system will perform better than a poorly balenced PC. I dont have any complain about my 2500+(@400fsb)/nforce2/ddr400/radeon 8500 AIW. If I ever want more speed, that will be the video card that I will upgrade.
But I can advise him to go with a 2500+ and run it @ 400 instead of the 333 fsb. I do, run well @ 3200+, but since my cooling is so so, I lowered the multiplier a bit so it show up like an 3000+ instead. It is synchronized with my ddr400 memory. fast, stable and cheap!
-Always put the blame on you first, then on the hardware !!!