Vista uses about 7GB of space, Microsoft just says it requires a 15 GB hard drive.
Vista Ultimate requires 7.4gb of space.
Wow that must of recently changed. Anyhow Vista still has a LOT of useless garbage in it:
For example it still has legacy icons for Windows 95! Microsoft said they are working to remove it but obviously with an OS of Windows' size it can get pretty tedius.
But seriously, that cleanup is one of the things that should be done to prep the OS for the component rewrite that Vista had. This isn't something you should be rushing for in the RC1/RTM stages.
I really think Microsoft employees
never want to upgrade Windows like this again. It was a horrible experience that even a company with as much resources as Microsoft could barely weather.
My money is on Windows become a more modular OS as a whole in the sense that you'd be able to upgrade say the Audio stack withought much trouble.
If they can do all of this behind the scenes withought breaking backwards compatability then it'd be good, else there is always VMs for backwards compatability. Hell, OSX did it with OS9 pretty well.