This is a very interesting thread.
I personally have used Win 98, Millenium, 2000, & XP Prof. I have come to get used to & like XP Prof. I have never had those problems some strongly anti-Windows users give the impression it is practically unusable. I spend mostly anything from 8 hours a day using the pc for different things, work, graphics, etc. The fact is after many years of the availability of Linux & other systems, Windows is it still on is it 90% of all PCs worldwide? Are all those users as *%&'X as some people suggest? It's certainly not perfect, but it is not as bad as is suggested.
I have tried Red Hat 9, Ubuntu & Suse Linux & prefer the latter, now version 10.2, which is much better than the 6.0 I started with. I have never liked Ubuntu, the interface looks quite lousy to me, though I read about all sorts of nice things about it.
If one has RAM of more than 512 MB, why not try another system by installing it via WMWare or similar programs, without getting rid of one's preferred system?
For someone having less RAM, or who may just find this option better & has enough RAM, a dual installation would be good, so that on booting, one can select whichever system fits what one wants to do at that time? That way, one can enjoy more than one world at a time, each with its advantages.