Well, we had the first real test this morning with 2 classes of around 25 in each. Things performed superbly. We have 3 classes running simultaneously this afternoon, it will be interesting to see how that goes.
Some interesting stats from mmCache as it records the number of hits to any particular php script.
c:\www\moodle\lang\en\moodle.php 28013
c:\www\moodle\lang\en\quiz.php 12993
c:\www\moodle\lang\en\forum.php 11154
and there quite a number of scripts with 3-5000 hits too. No wonder the poor machine was crawling having to interpret all of that.....
Pablo, thanks for your thoughts, but moving to Linux isn't really an option. This started out as a hobby of mine and will eventually become administered by the main school's technicians who don't know (and don't want to know) about Linux. All the other servers run Windows so it makes sense to stay with Windows. If it were my choice, then I'd switch, but I have to consider other factors.