if I had to buid DC from scratch, I would run the following setup:
Software, Specials and discounts, articels: Use a CMS - I would use Typo3 or Drupal - yes I know, we had this before (another topic), but especially Typo is so incredibly powerfull - yes, it has a huge learningcurve, but when your "in" the system you can do anything with it.
Documentation Pages: Some Wiki Software - I prefer "DokuWiki", but Media- or PHPWiki would do the Job also very good. Or Keep them in the CMS
BugTracking: maybe Mantis...
Contests, Reviews: for the Contents and Reviews, I would write a Extension for the CMS to keep them "structured", or keep them as they are
Forum: Hmmmm switching from one Forum to another without losing all posts isnt trivial. I think, I would stay at SMF and tune it a bit - another Theme, some Syntax Coloring Extension and so on
Podcasting: I never used any Podcastsoftware, but I heard loudblog (www.loudblog.de
) should be good