If you're looking to upgrade to Windows 7, or just to perform a clean installation of one of the older Windows operating systems, you probably don't want to reinstall your current collection of installed applications one by one. PCmover Professional ($60), unlike the free file transfer wizards found in the most recent versions of Windows, helps you with that--transferring your programs as well as your documents and settings.
Though PCmover will transfer via a Windows EasyTransfer cable, USB, or even external media, I opted to transfer settings from an existing XP installation to a pristine Windows 7 installation via a network connection. PCmover must be installed on both PCs unless you're performing an in-place upgrade or using external media in which case a "mover" file is created with the settings from your old installation.
There are quite a few steps to the transfer process. First you install and run the program on the destination and origin PCs. Most of the work is done from the old PC. PCMover connects to the new PC, makes a snapshot of the new PC, then allows you to map users, map the destination drive, filter files, and select applications. The application holds your hand through the process and I spotted nothing that should make the average user nervous. I do recommend that you peruse the list of programs to be transferred carefully--there may be a lot of junk in there that you no longer need, or never used at all.
PCmover worked perfectly in my migration with Firefox, Avira Antivir, Genie's Timeline, Acronis True Image Home 2010, and Gizmo Drive. All are functioning fine post facto. All my documents, settings, and users showed up in Windows 7 as well. There is a disclaimer at the beginning of the transfer that you may need to provide some serial numbers to get certain applications to run, or that some programs may not work after transfer. In other words, there are no guarantees. PCmover disables autorun programs that it doesn't recognize as a safety precaution, but after you reboot the system it pops up with a utility that allows you to enable them.
All in all, for effectiveness in transferring my XP installation to Windows 7, I give PCmover Professional an A+. If you don't have the time or don't want to hassle with reinstalling your applications (or you can't find the discs), it's a handy, albeit expensive, utility.