HTC Shift comes with Windows Vista only. There is no official support for Windows XP. But, Vista drivers seems to work fine on the Windows 7 (of course in compatibility mode). The snapvue also seems to work fine in Windows 7. To install Windows 7 on the HTC Shift, you will need an external DVD drive.

Here is a step-by-step guide to install Windows 7 on Shift. (thanks to deadnex at xda-devs)
• Download the beta image from Microsoft
• Burn the image to a DVD
• Enable wifi and Bluetooth in Vista.
• If you want to dualboot Windows 7 and Vista you need to partition your harddrive before starting the installation. Use a suitable partition manager such as Paragon Partition Manager and shrink c:/ to approximately 15-17 GB. Create a new partition in the free space.
• Connect the USB DVD drive to your shift
• Press fn+0 (F10) after turning on your shift – select the DVD drive
• Follow the steps for installing Windows. Remember to select partition 2 as target partition if you want to dualboot with Vista. If not you can safely format the existing partition. This will not affect the recovery partition. If you prefer to upgrade from Vista to keep your files and programs you can start the installation from Vista instead of booting the DVD. However, since Windows 7 is still a beta OS this might cause some unknown problems. I recommend installing a fresh copy and dualboot with Vista.
• Download the shift drivers from HTC Continue reading “How To: Install Windows 7 on HTC Shift [UMPC]”