Have you tried cleaning temporary files?
You would be suprised how much unnecessary space is taken up by temporary files, give it a go and see how much space you clear up.1.
Open Disk Cleanup by clicking the Start button Picture of the Start button, clicking All Programs, clicking Accessories, clicking System Tools, and then clicking Disk Cleanup.
In the Disk Cleanup Options dialog box, choose whether you want to clean up your own files only or all of the files on the computer. Administrator permission required If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
If the Disk Cleanup: Drive Selection dialog box appears, select the hard disk drive that you want to clean up, and then click OK.
Click the Disk Cleanup tab, and then select the check boxes for the files you want to delete.
When you finish selecting the files you want to delete, click OK, and then click Delete files to confirm the operation. Disk Cleanup proceeds to remove all unnecessary files from your computer.