Yes, i had Win XP for 5 years on my old PC and never a crash or troubles. Since about 1.5 years i use Win7 Ultimate on my new PC and have no troubles too. Microsoft has learned its lessons (except the troubles with the infamous Vista)... and since a few months i have Ubuntu on my PC (now dualboot) too... works fine too!
I have a Mac now. Got it last year in June and I love it! It's the Macbook Pro 2011 edition. You should get one. I have tried Ubuntu. For fun. But never liked it. My daily programs weren't for Linux. Like Minecraft
I have just "Ubuntu-rized" the old XP-computer of my dad. It was an old Pentium 4 with only 256MB RAM, but Oneiric Ocelot runs well on it, way slower than Ubuntu on my actual i7-960-PC, but faster than the previous Win XP on it. To be honest, the old PC wasn't started since 2008 anymore, and i was surprised, that it still started up without any problems after this long time. Win XP made 83(!) Updates and Service-Pack 3, but i still wanted to try Ubuntu on it. I never used OS X so far, only iOS on my iPad