BigBlueBall 0 Junior Poster in Training

I'm in the process of converting my site from ASP to PHP, and I'd like to use mod_rewrite to make sure all the search engines that currently have all my .asp pages indexed will take people to the appropriate .php counterparts.

That's simple enough for the "static" pages, but the tricky part comes with the forums. I'm switching to vBulleting and importing 80,000 threads using ImpEx. Unfortunately the imported thread IDs are different from the originals.

I'm thinking that I can probably modify the import to store the "old" thread ID in the new database, but how can I use mod_rewrite to direct people appropriately?

For an example, this is an existing thread on the current site (using ASP):

http://www.bigblueball.com/forums/topic.asp?TOPIC_ID=6846

And this is the same thread on my test site after importing (using PHP):

http://www.hisbuddyicons.com/forum/showthread.php?t=4866

Different IDs. With my very rudimentary understanding of mod_rewrite, it seems like this is do-able, but I'm not sure where to begin. Pointers, anyone?