Playing starcraft 2 setting all max ultra using my rig. all smooth,the best part even with trainer you spam countless unit full screen its still not laggy.

core i7 920 @4.2ghz ht off.
6 gb ram ddr3 @ 2000mhz .
ati radeon 5850 @1gb core clock @ cat 10.7 beta (sc2 patch).
samsung 42inch @ 1920x1080.
dell 2707 @ 1920x1200 iddling displaying various program.
window 7 ultimate x64.
rest of the spec is at my siggy.

but on this configuration certain game have some issue as it doesn't support dual monitor hook up even though the other monitor basically not doing anything.lucky starcraft 2 is not that heavy.

avoid official 10.7 at all cost, in my case its bsod on me, get the 10.7 beta (meant for starcraft2) that is much better.