Well, I will say this: If you think the zero day exploits and the 3rd party vulnerabilities are gonna stop just because it's a new OS, then you are wrong. As easy as point, click, root.
Keeping it on topic, MS needs all the help they can get, this is evident by there pleeding for help at the 2 major hacker cons held this year, where infact Vista flaws were exposed on stage(infront of Microsoft networking engineers) by a young lady not but a month or two after Vista RC1 release, I have the Whitepaper right here.
Computers were created with the purpose of accessing and sharing resources, and none of this revolved around fancy GUI's that can immitate Real Life.
I'm not a Microsoft Hater, I don't hate anyone.
Further, ppl like werner proffessing that they dont need antivirus products and using a weak antivirus product like AVG to prove it are very silly,giving reasons such as not visiting dodgy areas of the net as their point of safety, I would argue against that with the example that over 1 million users were infected with malware after visiting Myspace and being exploited by the WMF zero day vulnerability, You wouldn't consider Myspace a dodgy area of the net would you, think again...server comprimized....it was infact a Linux user who discovered that exploit when visiting Myspace and being prompted(unlike the MS users) to download a file with the ext WMF.
There are ZERO day exploits out there that are for sale, there is a market for them. Bad people bay money for them, and the harsh thing about it is these arent published on BUGTRAQ or Milw0rm...these are silent and are comprimizing MS boxes all over.