I have computer (desktop) I built a year ago and put Vista Home Premium on it.
It works fine for me.
I cant say I LIKE it as much as XP (I have another dekstop with XP on it) but my whole family use Vista and it works fine.
I get annoyed with the "Do you really want to do that" window (I know you can turn it off) and it is a bit sluggish compared to XP.
But overall it is not that bad (not great but usable)
There is a Vista service pack 1 which you should install, plus a load of fixes that go on top of SP1.
I you dont run Windows Update then you should, to get all the latest Vista fixes.
The next release of Windows will be out early next year, and that will probably be more like Vista SHOULD have been.