How it hangs together technically is quite different from xp, and as such thats where some of the fubbies creep in... things you would expect to do with an administrator account, you can't.
M$ are trying to force in some standard best practice with Vista with the user rights restricted unless it is required to do a particular task. They are trying to move away from the "I need Administrative rights" culture which is a massive, and fairly brave step forward. This also forces software developers to write their code properly, rather than relying on users with administrative rights, they have to use the proper api's. This may all sound like double dutch, but its really a very good thing and something the IT industry has been trying to do for years without success. Now IT departments all over can breath a little easier... in some respects.
One think I would say is if anyone is seriously thinking about buying new hardware and upgrading to Vista GO FOR 64bit!!!! It is really the way forward and all my apps run comfortably and all the mainstream vendours (and many of the small ones) have 64bit hardware drivers. The 64 bit platform runs 32 bit Apps seamlessley. This is far from the bad old days when 16-bit apps ran in the TWUNK16 subsystem of 32 bit windows.
BUT... if you are someone who likes things to stay as they were, forget it. Vista is a NEW opperating system and won't let you do many of the things you have been accustomed to in XP and its predecessors.

Just my tuppence worth.