(sorry for the double post)
Wait, I think you still need an antivirus/anti-malware system even if you are using "Deep Freeze". Remember, by using Deep Freeze, you are essentially virtualizing your machines, however, one can still install malicious software, keyloggers and viruses in that machine during the PC's use... those malwares would only be removed ONCE you rebooted the computer. Now, if you really plan to make workstations that lacks an antivirus program, do you plan to reboot your machines each and evertime a new costumer uses the PC?
The ideal answer is yes. Lalo na kung start pa lang ng cafe mo. But as time passes, youll get loyal and trusted customers. Kung sila yung mag a out, at alam mong inosente yun sa paglalagay/pagdadownload ng malwares, there really is no need to reboot the pc everytime na may mag IN na new customer.
Yung mga keyloggers lang ang problema naman talaga dahil posible ma hack yung customers mo. Other malwares (viruses, worms, trojans), hayaan mo lang yan hanggang sa next na reboot. Kahit kumalat pa yan sa network. Anong sisirain ba nyan? At the end of the day, mawawala rin yan.
Maganda kung ipaalam mo sa customers mo (yung customers samin, alam na alam) na naka deepfreeze ka. Kung gusto nilang siguradong keylogger free, sila na mismo mag restart nung pc.
Anyways, kung talagang mag i install ka ng antivirus, then hindi na advisable na sabayan mo pa ng deepfreeze. Imagine kung everyday, mag a update yung antivirus dahil frozen yung drives, araguy.