Re: For a long time, I was, in fact, quite happy with Windows 2000
"I only made the switch to XP because 2000 ended up unsupported, and there were a few very nasty viruses out there that could really ruin your day if you were running a Win2K box."
Not so; win2k is under extended support until next year, and may even last longer since MS have a habit of extending these deadlines. Critical (and Important?) issues are still being fixed under the same schedule as XP fixes.
"Win2K contained most of the advantages of XP, shared the same driver model and had stability in spades"
"there wasn't much of a compelling reason for me to go to XP - and I was a latecomer anyway - only switching from Win2K in 2003."
Latecomer? I'm still on Win2K in 2009 and will remain on it until they prise the extended support from me
Win2k, when used securely (with third-party firewall, anti-virus etc) remains MS's best OS in my opinion. XP offers little (nothing?) of use over win2k beyond what is already done better by third parties (Security software, Wireless LAN manager, CD burning), and removes useful features such as the three-pane view in Explorer, without which I remain in bewilderment about how anyone who uses their PC as a tool rather than a toy gets anything productive done at all.