System migration

In connection with my recent topic on building a new system, I started thinking about migrating my data etc.

For steam games, my plan was to back up my steam games in archives on the hard drives, and then install from that again. With GOG I also still have my original downloads.
I though I'd then just temporarily plug each of my harddrives into the new system, and then copy the archives and savegame folders. Same for my personal data.
I'll also export and transfer my internet bookmarks.
Since I am moving from XP to Win7 I see no use in exporting any settings or other stuff.

A bit of a head-scratcher is all the licensed (timed licenses) software, e.g. Avira, registry cleaner, etc. I guess I need to find out one by one if I can just reinstall or need a new license?

Maybe some people are interested in sharing their ideas and tips. What do you usually do? Are you using any specific tools?

I just plug-in a USB hard-drive and move over everything I need. Fastest and easiest.

There are specific procedures for browser settings (saved passwords for example), email software, etc. Google is your friend. Migrating Opera or Thunderbird from XP to Win 7 is no problem. It's basically a question of copying exactly the right files into a fresh install.