1) All IMHO, do not kick himself sitting without antivirals, but 30-40 usersof under different...
a) is not valid we have, as the option is not even considered never
b) the gcd sometimes it skips that you wonder(in the last time .lnk files a month after the announcement of the hole, when, long ago, and Casper and the web caught), although some comrades very much, works on the fact that VIR is already in force, but the system does not slow down.
C)the KOMODO is a good firewall, like AntiVir, I would not put.
AntiVir solutions — only from Casper or the web, but they cost money, and the first system hard brakes.
Remind all purely IMHO.
a)to limit accounts
b)to cut off the AutoPlay from removable media, it is better in different ways: XPTweaker, AVZ, XPAntySpy, PandaUSBVaccine
C)Deactivate scripting host: XPAntySpy
d)to cut off all of the USB ports on... really
d)to have latest updates of Windows
e)proxy firwall with antivirus, free for example at least nod\\avast
3)Yes, theoretically at least.