Hi,
Hvae recently run on a de-timetabled day a GAMEMAKER club, this club introduces students to the process of game creation.
you could either run the club as a structured learning session: review, plan, create, test, (loop)
OR
you could simply introduce them to the software, teach a few basics and let them go....
I recently ran several sessions to full classes, a little while in it was clear that the breakout style game i was making needed more blood and explosions....and off they went..
the site to visit: yoyogames.com.
The software does work on vista, but occasionally stumbles (apparently) i have had no probs....
incidentally the PRO version (as in paid for ) costs $20 and gives you more bells and whistles, PLUS the ability to save standalone EXE files....
good luck
Jason