Yeah, dude... Duemilanove is an official Arduino board. There's NO reason to use any sort of old, alternative, or "hacked" IDE to upload to it. Just go to arduino.cc and download the latest IDE.
Also, there are two versions of the MPGuino code floating around for some reason: an old version designed to work with the old ATMega168 chips (with 16kb Flash and 1kb RAM), and all current Arudino boards (and the latest MPGuino) run on ATMega328 chips (with 32kb Flash and 2kb RAM). I think the latest MPGuino code uses the ".cpp" filename extension, whereas the older, outdated code uses ".pde" I think.
In fact, I'm currently wiring up my Duemilanove on a test board to play around with some more code modifications... wiring it up just per the Wiki page (without injector/VSS, obviously), and using the latest IDE and my own customized MPGuino code.
