I've basically finished upgrading my laptop from Vista to W7. I had run the Upgrade Advisor and was not notified of any issues for the upgrade. After running the upgrade, something hadn't clicked and the system was in a boot/Blue Screen of Death (BSOD)/shut down/reboot repetitive cycle. Calling MS Help, my overseas technician basically had not enough training yet in the W7 install and spent a lot of time checking with supervisors. I was finally handed off to a higher level technician who then walked me thru a clean install upgrade. While I was unhappy about losing all of my programs and settings, I was able to get back to where I wanted to be since I had all of my critical program install discs and all the hard drive data files were copied to a folder named windows.old in the W7 installation. I also use a Firefox add-on called Foxmarks which can synchronize bookmarks, favorites and passwords between 2 or more computers. Once I added Firefox and Foxmarks, all of my bookmarks, favorites and passwords which had previously been synchronized to our desktop magically appeared on the laptop.

Overall, the only negative of the upgrade was the lack of good help from MS, once I got around that it wasn't bad. I do like W7, it seems to have taken the good improvements in Vista and added more, a lot better environment.
Once Marlene and I figure out what programs and data she has on the XP Pro desktop that come over easily (Windows Upgrade Advisor shows no significant issues; wants an upgraded driver for the scanner), we'll run the new install/upgrade for her. There are a lot more programs, and older ones at that, with very large files on the desktop, so I anticipate it will be a somewhat more extensive/intensive process. Also, I picked up another 4GB of RAM very inexpensively so we'll be installing the 64 bit OS. Not sure how that will fly with the old programs, all of which were 32bit.