There are now a few tools around, that let you dual boot either into Android or Windows from your Windows Mobile device, and here is another alternative.
XDA forum member LePocketPc has posted a tool for choosing the OS upon boot for your HTC HD2.
Primarily for those users who still use WM as their main OS, but still want the choice of Android upon first boot, the tool brings up a screen where you can select between Android or Windows. If you do not make a choice within 30 seconds, the tool will make the choice for you and boot into the last used OS.
For more information and to download the tool, visit the forum thread.___________________