When backing up an entire disk which is Windows XP Pro,the WINDOWS directory of that computer is not accessible from the tape backup computer. In fact the directory is not accessible from Windows expolorer and can not be made shared from the XP machine.

How do we get around this problem. Does it mean the days of Network Backups are over?

If the WINDOWS directory is not backed up and a disaster occurs, all the programs will have to be installed from scratch.