I know all about choosing "Upgrade" by running setup from Windows, and doing a repair install/upgrade in place. However, the particular system will not boot, it crashes with a bluescreen. In Windows XP you could boot the install disc and do an "upgrade" which would preserve the system and make it bootable again. Windows 7 prevents this, if you boot the install disc it only wants to do a clean install. I really don't want to install this system from scratch if possible. What to do?