dual cores are the hot stuff now in cpu choices. like what overclock said "multi-task" without any lag or issues. for me i can be burning files to dvd-blanks while playing cs, hl2 and etc. very great for multi-tasking users. like overclock said not many programs take advantage of the 64 bit dual core. yet there is the 64bit windows XP operating system which I DONT RECOMMEND. Just my opinion.

I'm waiting for Windows Vista.
If this pc is used for work/office work and etc any intel dual cores would be a good choice (depending on your budget)
for me i use my pc for gaming and working. but i've been sticking with AMD for a while so it's kind of weird for me to switch.