I think most HD2 owners have moved to either Android or Win7 by now and left Winmo long behind.
I have not bothered with Win7, most people seem to be currently running NAND Android builds as opposed to the older method of running it off your SD card. Just head over to the XDA forums, read up a little about it, choose a build and follow one of the guides to install.
Personally I still run Android off my SD card as I prefer the flexibility, I use it pretty much 24/7 but do also still use Winmo on occasion - btw are you running a custom Winmo rom or stock?