If you want to play the upgrade game, Paul Thurrott has some tips on how to work the various schemes Microsoft is using to sell Windows Vista.
Among the tricks are to get low-priced OEM and Family Pack versions.
It ends up being more of a rant about the Vista distribution system than a consumer shopping guide.
Another tip I heard recently: Alex St. John suggests buying a PC with Windows XP and getting a Vista upgrade coupon.
That way you get two operating systems for the price of one, and you have the option of upgrading to Vista or not.
Former Microsoft guys like St. John are probably more comfortable than most about upgrading operating systems. But XP machines do seem like a bargain all of a sudden.