Often we chose a smartphone taking account the OS it runs. Nowadays Android is the most popular platform statewide, the iPhone is the most sold smartphone, and Windows Phone 7 probably is the most rumored mobile OS, and people have been waiting this platform more to be done. Anyway, if you don’t know which one to choose for your HTC HD2– Android or Windows Phone 7, now you can use dual-boot option. For detailed information you have to meet Darrengladysz’s tutorial, from XDA-developers, on how to do that.
For this awesome deal you must have an SD card adapter/reader and partition software. Besides these, you’ll need two microSD cards (8GB or 16GB). The first one will help you to obtain a smaller partition for WP7, and then it’ll be copied to the larger memory card. There are many nuances, related with Windows Phone 7 features, so I’ll not irk you with technical instructions, and those who is going to do this themselves, can get the full instructions at XDA-developers.
You also have to remember it’s always risky to deepen in the phone so much, but once you have done it, I guess you will be proud for your HTC HD2.