Yesterday I installed Windows 7 in the empty partition of my laptop hard drive - the one that had held Windows Vista. The latter stopped working a few months ago, as did HP's rescue partition. It was very simple to install Windows 7. The only difficulty was finding the Windows boot manager after reinstalling the Linux boot manager grub. Windows had placed it on the former rescue partition, for some reason.
My next difficulty was to get Windows 7 to work with my Ext3 Linux home partition, where I keep my data files. Previously on Vista I'd been using Ext2fs. It turns out that this works inadequately in Windows 7. You have to go into the program on each startup and re-identify the drive letter. I tried compatibility mode, etc. Eventually I placed the program file in Windows startup folder.
The Linux partition was then recognized. Windows file manager identified it clearly, and Itunes was able to find my music there. But Picasa didn't recognize it.
I had difficulty getting some programs to start on Windows 7. Chrome and Flock browsers wouldn't install. With Flock, I changed to compatibility mode before the install, then it worked.
My final problem was that Windows 7 seems to make greater demands on the CPU than does Ubuntu. The machine heated up more, and shut down a couple of times. That happened for instance when Picasa was cataloguing my photos, while OpenOffice was simultaneously downloading. Probably the overheating problem means that it's time to get my laptop fan cleaned. However, it's significant that Ubuntu never reaches the threshhold that causes the computer to shut down.
All in all, I liked Windows 7. It has a few nice additions that make me wonder why they never thought of these before. Such as the concept of turning My Documents, My Pictures, into libraries that contain other locations.
I will use it once in a while to sync music to my Ipod, and maybe to edit movies (after getting my laptop fan cleaned!), since I'm still not as happy with the Linux options for movie editing.
At this stage, Ubuntu remains for me a better choice for general use - there isn't a strong enough reason to switch back to Windows 7.