Firstly, I'd recommend ditching Windows, and yes, that includes Vista. You see, most of the nasties in the wild are written for the Windows platform, and unfortunately it doesn't seem that Microsoft is doing anything too serious about changing that except to continue the cycle of releasing new patches all the time, patches which would be compromised in a few days at best, a few hours at worst. Frankly, I'm not confident in Vista at all, after all, I was able to compromise its activation within a few days of its release, and I'm no hacker...
In any event, this recommendation won't fly, I know that. Most people love to remain within the comfort zone, and Windows is the comfort zone.