I'm running SC2 on my 6-year old laptop. It's a Dell Inspiron 8600:

Processor: Intel Pentium M 1.6 GHz, Single Core
Memory: 2048 MB
Video Card: ATI Mobility 9600 PRO Turbo 128 MB
Operating System: Windows XP Professional with Service Pack 3


Graphics settings all set to low. I get the occasional in-game message to close other applications to speed up performance, but otherwise still playable. Takes about 2 minutes to load a level. I'm primarily a console gamer, so at least get to play the game is still considered OK