Desktop - Sabayon Linux x64, 1x Gentoo Linux x64 (virtual), 1x XP Pro x86 (virtual)
Laptop - kubuntu Linux x86 (Jaunty)
Servers (home) - 2x Arch Linux (1x x86, 1x x64), 1x Server 2003 Standard, 1x ESX4i.
No plans whatsoever to go to either Vista or Win 7, although - I did try one of the early beta releases of 7 and was very impressed with it.
I noticed there are a few people quoting their work kit, which doesn't really make sense to me, I mean I know there are people here (myself included) who could say things like XXX Server 2003 EE, XX ESX hosts, XXXX WinXP Pro, etc - which is obviously daft, as you've not bought those. 0.o