It depends. For home users the choice should be between Home Premium and Ultimate (I discount Home Basic--it's simply not worth the money). Ultimate offers far better network and file sharing management, so if either of these appeal to you, Ultimate is the one to go for.
Business users (I'm thinking here specifically of SOHO users) can choose between Business and Ultimate. If you want to be able to handle media files, I suggest forking for Ultimate, otherwise Business will do.
The information in this tip originally appeared in the Windows Vista Basics online class discussion and in Adrian's Windows Vista Upgrade FAQ on ZDNet.
