You can get a copy of VISTA from Microsoft at the moment, obviously not the full retail version set for release later, wheres the fun in that for Microsoft
Its a late beta version and just to give people the jist of it, if you bought a new pc now, as long as it is high spec, P4 over 3.0 ghz and around 1gb ram, you could always upgrade to VISTA in the future when you see and read reviews on its performance, Microsft get the blame for always leaving exploits etc but the reason this is, and it doesnt occur so much on say the Linux operating system or Mac is because after all the hackers do have a brain, they would concentrate on finding flaws within Microsoft suite as they know most people use this and the people who use Linux etc are the minority, and usualy people who use Linux are very litterate around compters so attacking them would be abit more challenging, if more and more people started using Macs then the hackers would turn their attension in that direction.