You can limit the amount of HDD space taken up by System Restore,
i.e. the number of old Restore Points saved.
Open System Restore
Click on System Restore Settings
Click on the drive if you have more than one
Click Settings
adjust the slider to suit[/list:u]
If you have extra drives, which you don't usually need monitored, make sure that they're turned off through
their Settings dialogue box. Otherwise you'll gobble up more GBs than necessary.