AMD Athlon Venice 3800+ and if you wait a little while to buy they well be droping in price and i think the AMD Athlon Venice 3800+X2 is gonna be down to like $170 or around there.
AMD is better at gaming and it can multi task (single cores it can't multi-task like an Intel can.) However it beign duel cores The AMD can multi task great and game which gives you rather 2 good reasons to buy the 3800+)
Intel:
Intels are good at multi-tasking and not so good at gaming you can game on a intel chip but it wouldn't be that great. However since the penitum D i beleive is dual core which allows you to multi task more but it doesn't improve on the gaming any at all since all the games only use 1 core when gaming.
However Amd is clearly the best choice since it allows you to do both.
The price might be cheaper but remeber what you pay is what you get.
No one hit of the fact that the AMD will consume LESS power and in turn run cooler.... If you leave your PC on 24x7 That is a big thing to think about, as well as the fact that near silent cooling on AMD 64's isn't hard to do.