Are you moving from the same type of DB (e.g., MySQL to MySQL) and keeping the same version of jForum?
If so, it's fairly straight forward to do this.
1) Set up jForum on the new machine.
2) Compare/merge your new site's jForum-custom.conf file with the old site's file.
3) Copy the images and templates directories to the new server.
Do a
test run first of the following process... then repeat on actual move day
1) Export the production DB using your DB utilities (e.g., MySQL backup/dump db tools)
2) Import the old DB info into the new DB
3) Copy the upload directory from the old to the new
4) Test, test, test.
You will also have to do the DNS swaps from old to new. This can take a while to propogate...
[originally posted on jforum.net by monroe]