Windows:
+: classical, gaming, popular
-: unsafe, unstable, fucked
Apple(MacOSX):
+: style, userfriendly, supported, safe, apps, stable
-: freedom, hardware(not expandable), overpriced, only availiable as full packets
Linux(Ubuntu(11.10))
+: style, userfriendly, supported, software center, freedom, (gaming), safe, free, stable, fast, open source, customizable, basic for things like: cell phones, android, PS3, much much more.
-: unpopular, not many games/programs for it
