minimum space available on 'C' OS drive...

Download and install CCleaner to tidy up your Registry. Backup the Registry as you go along, rescan again and again saving as you go until there are no errors left.

Cleaner: Windows

When you first open Ccleaner you will have an option to Analyze or Run Cleaner, after checking the left Pane and making your choices. Delete all Temp Files. If you scroll down you will see a greyed out box that has Advanced next to it. Left click on it and keep pressing OK to all of the responses. I normally Untick Windows Log Files and Memory Dumps as they may come in handy.

You don't have to install all of the add ons or shortcuts just the one to the Desktop.

http://www.ccleaner.com/download

Run Windows Explorer (windows key + e), go to Tools, Options and View, tick "Show Hidden Files and Folders", untick "Hide Protected Operating System files" and "Hide extensions for known file types". Then click apply to all folders.

Download WinDirStat and check through the folders for any large files in C:\WINDOWS or any repetitive files. Turn on the Show Free Space under Options.

http://windirstat.info/wds_current_setup.exe

Another way to find wasted disk space is to use the Disk Cleanup tool by following these steps:

1. Open My Computer, right-click Local Disk, and then click Properties.

2. On the General tab, click the Disk Cleanup button. Disk Cleanup will spend a few minutes examining your disk.

3. The Disk Cleanup dialog box will open and you can make your selections.

4. Select the desired check boxes in the Files to Delete list.

5. Select ?Disk Clean Up and other options?. In the ?Other options? press on ?Clean? for ?System Restore", and then click OK

6. If you have more than one hard disk, repeat this process for each hard disk listed in My Computer.

Maybe you have a hiberfil.sys. I've also seen systems with 2 swap files (one defunct). Look for pagefile.sys in C:\; C:\Windows; C:\Windows\System32

To fully view drive space available, right-click C: drive and select Properties.

How much free space do you now have, after running Disk Cleanup and CCleaner ?

Also, you have to understand that your hard drive probably NEVER had 10GB in the first place. the 10GB name is the marketing name given to the drive by the manufacturer BEFORE the drive was formatted. After it was formatted for your system's operating system it was more likely to be somewhere around [u]"nine point something GB"[/u]

If you still do not have sufficient free space to defragment, download and run TREESIZE:

http://download.cnet.com/1770-20_4-0.html?query=TreeSize+Free&searchtype=downloads

This will allow you to scan your C:\ hard drive and see where the largest files are sitting. It will also show you which directories are occupying the most space.

What you see from this scan might show you some files that you had forgotten you have - files that you could easily delete without actually 'losing' anything. :)