Once that premise, to have two operating systems simultaneously on our HD2, Android should be on SD. Then you can not have both in memory and Android WP7 Nand.
Having said this, how to create an SD CARD to have a dual boot between Windows 7 and Android on SD ?
As we know WP7 uses a special format for formatting the SD card and you can then simply copy the SD Android phone after you install Windows 7. WP7 will also create a FAT32 partition of 200 mb, but this partition is too small to install android. What to do then? Here is a detailed guide to follow step by step: