WinXP is where I'd love to stop. As a Support Guy... I love remote desktop and remote assitance that is built into WinXP Pro. No need to try another 3rd party application to do it. No problems with kerberos authentication, no problem with privilages, no problems with conflicts... Remote Desktop/ Assistance just works.

I'm know that my company will be 10% Vista-ized by this time next year.