i have been in troubles with the windows restore points in the last days...
1. virus were infecting it a whole week long
2. defragmentation stops at this points for hours!
3. diskspace (wasnt a big problem though)
System Restore points can use up to 12% of your entire diskspace!
so you may think about deleting them!
i advise to take the first way, because its does not delete your last made restore point (having a restore point is nice, if sth messed the registry up, etc)
How do I delete restore points in System Restore?
You can either delete all restore points except the latest one, or all the restore points:
- To delete all restore points except the latest one - Use the Disk Cleanup utility. Click Start, All Programs, Accessories, System Tools, and then Disk Cleanup. Click on the More Options tab and then select Clean up in the System Restore dialog box.

- To delete all the restore points on your computer - Disable and re-enable System Restore on the system. Click Start, Control Panel, and then the System icon. Click on the System Restore tab in the dialog box, select the Turn off System Restore check box, and click Apply. Clear the check box again to re-enable System Restore and then click OK.
you can also the limit the space the restore points are allowed to fill.
open system control and open the entry called "System" ---> click on the tab "System Restore" --> set an appropriate limit by moving the arrow.
finally, i used the first method...