But often the GUI is the last thing they change - Longhorn (early betas of Vista) were basically recoloured versions of XP with a few extras here and there.
Granted, but it has a Celeron CPU, 512MB of RAM, an 80GB hard drive and Windows Vista Home Basic. It runs like a slug and has a WEI score of 1.3.
I wish that I had a laptop that scored 4.0.