I Work/Study in a college which is almost completly microsoft based (windows, office, visual studio) which is not such a bad thing with the discounts we get on software as a college but with several students doing web design and only internet explorer to test on i have been bugging the admin to install firefox (hes probably going to read this when i send him here so "hes a nice guy who knows everything about the network and always has time to reply to your emails"
anyway although i and several staff members have explained that firefox is free and opensource but as we are a member of FAST (http://www.fast.org.uk/) he is very weary about installing it network wide, have there been any releases or anything that i can show him (apart from mozilla sites of course!) that will prove to him about licences, a word from FAST themselves on the program would be perfect.
The MPL is considered by gnu.org to be a free license but incompatible with the GPL [gnu.org]. However, the license is almost certainly wholly appropriate in your case - as a Windows shop, you are not using GPL software anyway.
There are few restrictions on redistribution or installations, and as you would not be looking to significantly alter or re-use the code, there should be no issues blocking its use.