Turn Off Grammar or Spell Checking in Word
Some people really don't like having Word constantly remind them that they've made - what Word perceives to be - errors of grammar or spelling. Well, if you want to turn off the little green or red squiggly lines you're in luck, you can.
In Word 2010 go to File | Options and select Proofing from the navigation column on the left.
To turn off Grammar checking uncheck "Mark grammar errors as you type" and you may want to uncheck "Check grammar with spelling" too.
To turn off Spell checking uncheck "Check spelling as you type". That doesn't prevent you from running a manual spell check (press F7) but will prevent Word from colorfully annotating your text as you go.
As long as you're on the proofing options you may want to tweak the AutoCorrect and other proofing options to your liking. There are some powerful tools in here.