Windows 7 is a marked improvement from Vista, in my opinion. I upgraded XP to Windows 7 in about the same time as it takes to do an XP reinstall. The UAC and permissions were much better and almost everything dropped into place.
I had a problem installing Matlab 2007b, fortunately compatibility mode fixed that (standard Windows 7 created odd icons and wouldn't get past one of the early screens).
Then I was running beyond compare for my standard synchronization and wham, many files were "access denied." I went to the explorer to see if I could delete those, and presto UAC was the issue. A quick google search revealed that a simply change to the properties of the shortcut would work, and it did. Windows 7 is still going strong (again in my opinion).
