I think I have the same model Rotozip as Zakk. The thing is impossible to use unless you just don't care what the hole looks like. My Dremel on the other hand has been used up the ying (not my ying). Love that thing. I got the $80 variable speed set that has some extra attachments and the extension cable. Then I got the holy bajeezas set of bits at Costco for 20 bucks. Second best tool ever. I love my Kreg pocket hole jig more
.
I went to the hardware store and got the same kit. I really wanted that variable speed Roto Zip with the angled circular saw attachment, but this kit will get more use with hobbies and such. The harware store guy also mentioned that I could use either one, but if I was going to do heavy work all the time (like installing drywall or countertops daily) I should take the Roto Zip. The Dremel was cheaper and came with the router and flex shaft too. I also picked up the circle cutter for $9. I think that I'll be happy with all this.
But now I have a problem of having no circular saw for light use. I'm building this thing with my soon to be father-in-law, who has a heavy duty circular saw for the cab. I thought that the Roto Zip attachment saw would be perfect for CP revisions in the future. Are there any small circular saws that are in the $30-$40 range that would be good for cutting 3/4" MDF???
Also, while I will of practice on some scrap wood, are there any good sites that can give me some tips on using this thing? And what about bits?

What will I need for cutting the MDF? The kit came with a drywall and general purpose bit, so will the general purpose bit do the trick? What specific bit should I purchase for the T-molding slot? I saw the $30 bit on the T-molding site, but I really don't want to pay that much unless I really have too. Plus, I need it for this weekend.