One more thing concerning the site conversion that I guess you're already aware of:
The old forum software didn't leave dummies and then rendered them when the pages were viewed, but instead it directly replaced it with HTML code when a post was made. One such example is the use of smileys:
For example, for

, instead of a smiley tag, it directly placed the code
Code:
[img]http://forum.shrapnelgames.com/images/smilies/happy.gif[/img ]
in the text. It shouldn't be too hard (a mere search-and-replace job which can be automated) to replace those hard links to the image URLs.