This is my personal experience of how I spent around 10 hours to get windows 7 professional upgrade installed in my box.
At the end when I was so much irritated and upset that windows 7 upgrade did not install in my box and about to switch off my system and wanted to run... run run away, something in the corner of my mind told me to give another try and it worked
The problem I found was surprising. My system has 3 hard disks and 2 has debian installed on it and one of them windows . The problem is windows could not install/upgrade if the windows hard disk is not set as first in the bios driver order
Without knowing this, I wiped clean my windows installation. Fortunately, I took a copy of my ntfs partition as a tar file inside debian.
(Mount ntfs partition containing windows inside linux (ubuntu/debian/...), select Ctrl +A and right click, create archive, select archive format as tar and save it in your home partition for extracting it later)
So when something in my mind pricked to try again, I booted into debian, created a new ntfs partition, extracted the contents of tarball (zip) of ntfs partition in the newly created ntfs partition, set the boot flag on ntfs partition and rebooted
I just changed the hard disk order in bios to bring harddisk with windows as the first. Then started my upgrade and it went without a hitch!!
After installing, I modified the hard disk order (back to make debian boot first) in bios and changed my grub in debian to bring an entry for windows 7.
Now I wanted to share my experience so that someone can change the hard disk ordering in bios to give windows 7 upgrade another try when they have multiple hard disk
Here is a screenshot of both windows 7 professional and debian
Windows 7 looks shiny and gorgeous.
You know, there is a proverb "All that glitters is not gold"