Is poolmon or an Equivalent Tool Available for Windows Server 2008

The WinSxS directory doesn't take up nearly the space reported by Explorer since it uses Hard Links to physical files, not actual files. Explorer just has issues reporting the size of hard links.

This article on Disk Space (referenced here http://aspoc.net/archives/2008/11/20/winsxs-disk-space-and-windows-7/) has a great explanation on the WinSxS directory.

As to your actual disk usage problem - You can try to run COMPCLN.EXE to see if you can clean up any old service pack and hot fix files, which should help quite a bit. I would also look at any logging directories to see if theres something else going on.

I don't think that what you're asking is strictly possible without cracking every local account's password. It's not possible to just "export" local accounts with their passwords intact. It may be easier to upgrade the current server (after taking a VERY verified backup) to Server 2008, and attempt to image that onto your new hardware.

Yes, that's painful, but the closest thing to what you're asking for.

If you were to import them to your AD domain, I'd do it to an OU with VERY limited rights. I'd certainly set the "Logon To" property to a dummy computer account (or maybe the IIS server), and deny "logon locally" and remote desktop for that OU's members.

Another option would be to create a separate domain in your DMZ for these users, but I'd still be pretty restrictive about what they could get to...