Just saw this post and figured with all the Starcraft 2 players we've got around these boards it's worth noting. There's an issue with the game that can overheat graphics cards because the ingame menu screens (like the bar, etc) aren't framerate limited.
To fix it (probably good to do even if it doesn't cause issues for you, just in case):
-Open Documents\StarCraft II\variables.txt
-Add the following 2 lines to it:
frameratecapglue=30
frameratecap=60
Source: http://gameinformer.com/b/news/archive/2010/07/28/blizzard-confirms-starcraft-ii-overheating-bug.aspx
