WinMo 7 or Android?
As far as android goes, I'm running it as a second operating system on my hd2 now by using a dual boot program and system which I found on xda developers web site.
Just do a search for xda developers and once you're on their site, do another search for hd2 android.
There a a few versions of android available to download with the install instructions. I'm running Froyo now and it's a pretty system but a tad glitchy. The bugs are being worked out every day.