Windows

Add another LARGER HD and map it as C.

I was just wondering where your pagefile file was situated. If it is situated on your c: a good practice would be to put it on another drive with the right amount of disk space. Take into consideration that your pagefile must be 1 1/2 more then your actual physical memory.

As noted above, check your swap file.

Also:
1) Move service pack and hotfix uninstall information from Winnt to another drive.
2) Check users documents and settings for any large temp files.
3) Check c:\winnt\temp.
4) Check for any user.dmp files these may be the same size as your pagefile.
5) If you are not adding anymore users frequently you could move clntapps folder, maybe temporarily?

Will post again if I think of anymore.

There may be a ton of log files on the C partition. Also, check for profiles that are unnecessarily huge, either from temporary files, or from files saved on their desktop, etc.

As suggested you can set your pagesys file (virtual memory) to another drive.

You can also reduce the size of your recycling bin, default is 10% of drive and 1% works just as well (right click >> properties).

Also reduce the size of the system Restore allocation via Control Panel >> System default is often 10 to 14% anything over 200 MB is usually sufficient. If changing delete old restores first, button to do this with the restore settings window.

Also the default temp file store is usually c:\windows\temp you can create a temp file on another drive and reset the pointers in Control panel >> system >> advanced >> environment settings and the registry settings for each profile. NB delet the contents of the existing directory regardless of what you do about and same for the temp internet files one below.

Ditto the C:\windows\temporary Internet files it can be changed through MSIE Tools>> Internet Options >> Temp Internet Files 'Settings' button >> change folder.

If everything was in their default settings this should free up about 30% of the drive that you had not been able to use before.