If you are not willing to use windows Mobile and want to use Android 2.1 on your HTC HD2, then this guide is for you, Installing the Android 2.1 on the HTC HD2 will not replace your current windows Mobile operating system. New OS will run through another application named Haret. You can get back to Windows Mobile by doing a software reset: push the little red button under the battery cover, using a stylus.
Step by step to install Android 2.1 on the HTC HD 2
1. Download Android 2.1 for the HTC HD2. This is a .7z file that’s why you will need WinRAR.
2. Connect your Htc Hd2 phone to the PC, using an USB cable and mount the SD card.
3. Extract the files which you downloaded above in step 1 and copy them into the root folder of your SD card (not into any folder).
4. Unplug the phone and using the File Explorer ( on Htc HD 2 ), find the files you just transferred, named Haret.exe.
5. Double click on Haret.exe and you’re done. To get back to Windows mobile, follow the instructions above the guide.