Remote control through firewall

I don't know about you guys, but I help a lot of friends and family whenever computerproblems araise. And recently I had to help my mother-in-law get her new laptop on the wireless network I installed previously. I though it would be a simple thing, but I guess I was wrong.....

It is really hard to help out someone when you can't see the screen and messages that appear, and I was despearte to find a way to remote control her laptop. After looking around I came across this neat software from TeamViewer (teamviewer.com). It is free for non-comercial use, and worked across firewall and NAT's. All I had to do was to get her to plug into the LAN and download the software. The best part about the version I found, is that it runs without installing. You just need the .exe file somewhere on you disk.