I used acetone for some caked on crud that came with the cpu (lol - the ppl at the comp store tested it for us and did a really sloppy application of white crap), and after that i used isopropal alchohol to clean it (the rubbing alchohol didnt phase the dried up zinc oxide paste). However, i would NOT use nailpolish remover, even the "good stuff" that has real acetone in it (some have some eco-friendly stuff... total crap), because nailpolish remover has crud in it that will be left on the cpu after the acetone evaporates (Pure acetone is totaly clear and doesnt have any perfume added). I recomend real acetone if you need somethign that strong. $5 or less at home depot for more than you will ever use. I used cotton balls to wipe off the thermal paste.
-Az