I noticed that if you install and activate an Alawar Game in XP, and you have other logins/profiles/users on your machine, the game won't be activated for them. Instead, it will open as a trial/demo.
If your children have their own profiles, and you install and activate under your account, you will need to log in as them, and run Activate.exe. Otherwise, they won't be able to play as a registered user.
I learned this the hard way with Pac-Mania 3. Thought it was worth mentioning.
Maybe this fact could be included in the Readme.txt for Alawar games.