There is a huge number of Android builds available for the HD2. Take a look around the HD2 Android Development forum for Build threads. Personally, I recommend Cyanogenmod based builds.

HD2 Android Development: http://forum.xda-developers.com/forumdis...

Within each thread, read the post and a few of the last pages of replies (earlier replies may refer to earlier versions of builds). The post should tell you any specific features to the build and any apps bundled with it; the comments will help you identify any problems you may face with that build.

Builds are essentially installed by dragging/dropping the provided "Android" folder onto your SD card.