I like AMDs better than Intels and I think they perform better but it really is a matter of personal opinion. I play with guys who have Intels and the rest have AMDs and both seem to perform well but the AMDs are better in most games. I would buy the AMD because I like them and the motherboards for them are better. They use DDR 400 which for the moment is better than DDR2 and later you can put a dual core in it. AMD dual cores are much better than Intel ones.
AMD's CPU is cheaper. And better. See the prices on Most Computers the third ones in the column(those are with VAT). The mobos for the AMD CPUs are a little bit higher than for the Intel ones but the superiority of the AMD is unquestionable as the tests show CPU charts. I can think of no stronger arguments. Your choice should be obvious.