If you have imported your IPB database into XenForo, you can automatically redirect all traffic destined for your IPB content to its new location within XenForo.
All that is required is that you unzip these files and place them in the directory in which your IPB files resided. The included .htaccess file will take care of redirecting calls to IPB into to the ips2xf.php file, which will in turn redirect traffic to the appropriate traffic to XenForo.
Any requests of the old URLs will...