I can't believe how good Win7 is. It's like it came from a different company. As a long time user of PCs, Macs, various flavors of Linux, and varying workstations from SUN and Silicon Graphics... if Win8 further improves upon Win7, I'll be sold on MS OSs.
My last Silicon Graphics Indigo and Octane2 work stations from the early 2000's had rock solid IRIX OSs. Both machines retailed at about $30,000 each. I had a post-it note on each machine for how long each were running without a restart (sorta like a construction site signs displaying how many accidents). My Indigo went 384 days and Octane2 went for 299 days without a shutdown/restart. Neither were shutdown for problems... the Indigo for an upgrade. The Octane2 shutdown for a move to a different spot in my house.
Windows XP... pretty much 2x times a day I had to restart. Never went more than 3-4 days till I had to shut it down because things slowed down. Then a lot of shutting down for security and OS updates.
Vista 32 bit... didn't have to shut it down through out the day. I did notice things slowed down after 3-4 days hence a restart. At least one shutdown a week for a update.
Vista 64 bit... same as Vista 32. Never seemed faster than Vista 32.
Ubuntu... never had to shut down. Period. Just works.
Windows 7 - I've been running it and the only restart is for updates. Maybe 2-3 times a month. Runs like a champ. Might be ahead of Ubuntu and my SUN and SGI machines considering how much harder I push my Win7 system including lots web surfing.
If Win8 is even more bullet proof and DOES NOT REQUIRE additional security software like SpyBot, Malwarabytes, Norton, Avast... sign me up. I don't care for more features... just more reliability, compatibility, and affordability.