Can it hurt to upgrade Windows 7 drivers?
To answer your question - No, it won't hurt.  But it may not work.  As with any driver upgrade there is no guarantees.  But there is no harm in trying.  You can always revert back if it doesn't work.

If you find it doesn't work, hold F8 whilst booting into Windows to prompt you to boot into safe-mode.  When in safe mode you can revert your video driver.

Let us know how it works out.  I doubt you're the only person playing SC2 on Windows on a Mac ;)