Chaim,
I was just checking to see if they had a 16mb machine *s*
If it's NT then you can easily tell from the Task List how much memory each app is using. In Win9x the System Monitor can show you total memory used.
A normal "quiescent" VFP might be using 6-16 megs. Do you have lots of big cursors in the VFP code? Does the problem always occur or does it only occur after they've done something like print a report?
>128 or 256