At my work we have an MSDN enterprise site license subscription, which means all MS products are pretty much free to me.
I am also going to the MS roadshow next month and I'll get free retail copies then as well. However, I am not going to put vista on any main system. I will upgrade one of the help desk work stations with vista and see how it runs first. 64bit driver support still kind of sucks, and I can only imagine every spammer, hacker, etc is going to want to be the first to exploit vista.
I'll wait.