L2R2R, you forgot Windows NT4 and Win 2000, no idea why you would run the alternatives back then unless you had to. I used to work as a graphic designer and ran Win NT4. I knew a lot of people running MacOS back then (pre OSX) and their machines would crash daily, mine crashed a couple of times a year. There were some drawbacks, no USB support in NT4 was one, but it was so far ahead of Win95 (and Mac OS9) it just wasn't funny.
As for Linux, a couple of things to watch out for: Adobe don't support acrobat on linux - this would be a killer for me at work but at home is fine. I often need to create, edit and stitch together acrobat files at work. We have one system at work which will only run on windows (uses .net) so again a killer for work, although given how bad that system is (along with all of the rest actually, why are large systems so bad (slow, clunky, bug ridden etc) these days, is it just lazy programming, I don't know) we would be best off finding a better one.
I understand the point about vulnerabilities not being fixed, but given the smaller number of users Win7 won't be the main target any more. I also hope Zone Alarm will keep it safe and I presume there will be some sort of hardware firewall on my router. In any case I rarely get viruses as I am fairly careful. Although, I do remember the first scam message I ever got, this was decades ago and these things weren't known about back then. The mistake the scammer made was to ask for my banking details for my Citibank account, I have no Citibank account! From then on I knew to be careful.
DS