We have co-op students working in our office and want to restrict
their visits to approved web sites (how do we do this in FireFox)?

Some of the websites on the available list are ones that we develop.
These web sites receive graphic files such as .AI, .EPS & .PDF, which
can be saved easily to the folder on the user's machines (using IE).

Our problem in IE is that when we turn content on the student can not
save .BMP or .JPG files to their computers and this is why we are
thinking of switching to FireFox.
Can we have better results with FireFox?