We use a 2 identical USB drives for backups on a Windows 7 PC. The drive is swapped each day to make sure that there is a good copy of all recent data at another location. We get full backups each night and I am not sure if this is due to changing the drive each night. [This is just curiousity] Since the backup is about 150Gb, we run out of room on the USB drive. I know that we can manually delete backups, but I would like a way that older backups are deleted to make way for newer backups automatically. [This is something I need to be able to do, so any help would be greatly appreciated]

Windows Backup should be incremental. That means the backup file should not be so large every time. However, if you enable "Windows Media Player Network Sharing Service", it will update the ChangeTime of all media files under c:\Users\Public folder every time machine is rebooted or resumed from sleep, so Windows Backup will back up them every time. To resolve this issue, turn that service off.Arthur Xie - MSFT