I would try to upgrade to one of the later 3.3.x versions first.  But, you should be able to do this.  Taking smaller steps is probably a better route that going all the way in one step.

Remember to make backups, and don't do the upgrade on a live site.  Instead, install your "live" site on a test server and do the upgrades there.  After testing to make sure that everything works on the upgraded site, you can then move it to the new site.  Remember that 3.x to 4.x requires going from ASP.NET 1. to 2.x.  There is a tutorial at the DNNCreative.com site if you are a subscriber.