It's the same on Vista as it is on XP (well, almost)
Start | Accessories | System Tools | Disk Cleanup
Click on Files from all users on this computer
You'll get a UAC prompt if UAC is enabled.
Select the drive and click OK
It will check the disk, then bring up the Cleanup dialog.
Click the More Options tab
The bottom section allows you to delete all but the last System Restore point.
I don't know if it will keep the latest version of any Shadow Copies of files, or if it deletes them all.
HTH
Jerry