yeah if your that bothered about gettihng some space back download the trial of tune up utilities
run it and select
Free up disk space on the left
let it run then click where it says
uneccesary files and backups , too see what you can delete , you have already deleted the SP2 backup but there will be other updates still stored you can delete , its also an easy way to delete all but the last restore point
I got 10GB back using tune up , its not really a good idea to delete restore points your better off limiting the ammount of hard drive space system restore uses , and of course after deleting the service pack 2 backup yuo have no way of going back if you have any issues , not that any of this bothered me
