Livre d'Or

I have XP running on one laptop, and Vista on the other. So far, I've found Vista to be every bit as stable and usable as XP. Vista changed some user interface stuff (control panel rearranged, sidebar added but can be turned off, alt-tab behavior tweaked somewhat), and I seem to recall reading that Win7 keeps those changes, but I haven't tinkered with it myself.

The only thing about Vista I truly dislike is the clumsy handling of administrator status. Even when logged in as Admin, it requires specific permission to change certain settings or perform certain file operations. It could really use a utility to smooth that out, particularly if the user knows they're going to need admin rights beforehand.

My suggestion is to find someone who's got a Vista or Win7 computer, and use it for a while to see whether there's anything that you really can't stand.