I tried to leave, really I did!
I'm sure it's not what you want to hear, but I'm all for reimaging
desktops now. I've had to start doing it at University Relations (MUCH
smaller installation). I had a friend who was sysadmin for a high
school with a few hundred computers and he swore by Altiris for
managing and imaging windows stations. Maybe something like that
combined with locally installed copies of something like malware bytes
for quick fixes?
We're using clonezilla here at the office for imaging. Perhaps if you
could set up a box in each office that the computers in that office
can netboot from you could use that for reimaging, and then just
periodically refresh the images on those boxes as needed? I don't know
how diverse the installation base is that you have on extra software
past the operating system though.
--nick