AFAIK a lot of engines will not use a javascript redirect, they'll die on the page.
For a redirect, you could use a 302 redirect with .htaccess files, or the redirectors which came with the UBB.T7 importer.
Myself I have a 302 redirect in the old directory (/ubb/) forwarding all traffic to our new directory (/forum/) then I have the redirectors sitting in the new directory.
