I am in the middle of a tedious conversion from post-nuke to drupal. I am picking and choosing what content I want to move over, since I have to write specific code for each module by going through the post-nuke database and finding all the related data (which is usually way harder than I would have expected) and then comparing that to where similar data is kept in the drupal database and then write some sql to move the data over and blahdy blahdy blah.
It's easier (for me) to do this one module at a time, and it also allows me to have SOME content up while I'm working on it. Really, the hardest part is the translation between the odd way post-nuke's database is set up and the odd way drupal's database is set up. There are way too many joins and ifs and whens and buts. I just made up the buts part. There usually aren't any of those. Unless there are. If there is something on the site that you particularly liked, please be patient. It will likely come back at some point.