Most people who complain about Vista are just a bunch of sheep who complain because thats the "cool" thing to do.
A small number of programs do not work on Vista, but most that didn't have been updated to work with Vista.
I have been using Vista for about 6 months now, there is one program I used to use which I would have liked to keep using, but I am fine without it (it was Sygate Personal Firewall, the program was sold off to Symantec and ruined, the old version which was still good hasn't been updated for years).
One of the first things you will want to do when you get your new computer is get rid of all the crapware on it. Like the trialware, like Norton, etc.
Also, which computer are you looking to buy? Maybe I can find a better one for less.