Get ready to get technical. This is for pros, not newbs. If you need to know the difference between a pro and a newb, check out the video below the content in this post. If you are a pro, continue reading. A fellow with one of the greatest screenname/handles I've ever seen, Snarksneeze, has posted to XDA Developer Forums with a big fat set of lists showing the world how to install a NAND Android ROM on your T-Mobile HD2.
Incase you're unaware, NAND is your phones internal memory. Recently there's been more and more people being able to boot all sorts of fun stuff off their NAND memory instead of just their SD cards. This is a good thing, because the lower you boot, the more stuff you can do (like installing Android on an HD2, which is, of course, a phone that usually runs Windows Mobile 6.5. Simple stuff, but really really hard to do if you have no idea what you're doing. Now take a walk over to the thread How to Install A NAND Android ROM On Your T-Mobile HD2 and learn - that is, of course, if you've got a HD2 to be working with. BUT BEFORE YOU DO THAT, remember to watch this video and learn if you are newb or pro. Serious.