Did you export the sites in the Manage Sites window before uninstalling? If not, then you have to redefine the sites all over again. If you did you should be able to re-import the sites.
Thanks. Unfortunatley I did not Export so I understand from your comment that I create New Sites. Alan
See Backing up and restoring site definitions. Site definitions are stored in the Windows Registry. If you wiped the registry to upgrade to Windows 7, your previous definitions will have been deleted.