I gained 512MB and another way to gain space is to set a new restore point on your PC and then delete all previous restore points. You would only do this if you are happy that your PC is working well and you dont see a need to restore to a much earlier time.
Go to Start / Programs / Accessories/ System Tools/ Disk Cleanup/ Then go for the “More Options” tab and click “Clean Up” on the System Restore option.
Paul