Runs fine on my 2.2 core 2 duo, 2gb ram and ATI 2600 (256mb) hp laptop with vista. No lag or anything that I have noticed.
Only problem I have is the mouse not lining up with buttons in the options menu. So I have to move the mouse pointer to the left of each button to get it work.
odd... maybe change ur resolution ?
a laggy options screen normally indicated laggy gameplay ... i was surprised to find not a single bit of it on my otherwise slow pc
*NOTE: at point of installation, my xp box has already been up for 2 weeks, and a few hours. It survived COD4 install and clock, bf2online, burning disks and pulling torrents. All legal torrents ofcourse - so the pc wasnt even at its peak to begin with *