Just thought i would share how I've done a VB3 on domain1 to Xenforo on domain2..
I do a permanent redirect on domain1
RewriteCond %{HTTP_HOST} ^domain1\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.domain1\.com$
RewriteRule ^(.*)$ "http\:\/\/domain2\.com\/$1" [R=301,L]
(you can use cpanel to...