i think it would depend on how seriously you're going to be using the programs. for someone who uses them non-profesionaly (not to say you're not good with them...just not for a business), the XP would be the better chip. when you're not using apps that support smp you're just wasting that other cpu. but if you'll be using those progs a lot, the dual sys is probably worth the money.
besides, niether is going to be very slow anyway.
no vestige of a beginning, no prospect of an end, when we all disintegrate, it'll all happen again.