I need to increase the server storage space. Does anyone know how to do this please? This is a windows 2003 terminal server and MY OB and other third party softwares are installed into this server with 120 GB storage space. Now only 1 GB free space is left and the normal file operation is not allowed due to this small free space. I have uninstalled the unwanted applications and user profiles, but still we get only additional 500 MB free space. Any help would be much appreciated. We don't prefer to touch the older applications data such as MY OB files.Thanks.
Windows 2003? If it's been in service a while, you can probably delete the uninstall folders for the hundreds of updates and service packs under c:\Windows. They're hidden and listed by KB ID.
Aside from that, you either need to migrate to a new server or add another drive to store user profiles and other data. A Windows 2003 system drive can theoretically be expanded, given RAID controller support and 3rd party utilities, but I do not recommend it.
Edit: I also recommend taking a look at WinDirStat, though there are other similar programs with the same result. It's great for finding what is using your space and visualizing it.
When forced by the limits of an old 2003 server, I've removed those KB directories dozens of times without a single issue (when I had no other short-term options). When was the last time you needed to uninstall a service pack or 2-year old windows update anyway? To me the other option is P2V. That's easier then upgrading the drive. But if you're concerned about some abnormal behavior of deleting those uninstall files, don't be :). It's better then a down server.
If another drive seems to be your only long-term option (cough P2V cough) then you can move the pagefile to get some space back quickly. You can also easily move the printer spool if it's a print server (default to c:\windows\system32\spool\printers).
Files that are not needed for a server to function properly (OK to delete in a pinch):
As @Hyppy says, space analysis is your friend. My favorite is the free SpaceSniffer.