Will the software be used in a commercial environment? If not, then you could use AVG from Grisoft:- http://free.avg.com/download I've used it for a couple of years now and haven't had any problems. Come to think of it, it hasn't found any viruses either!?!?! Perhaps I've been lucky, but I prefer to believe my email server is fairly good at rejecting spam etc.
I'm sorry but stay as far away from them as you can. AVG 7 was great, I used to recommend it all the time, but version 8 has become really bloated and chews through resources like no-ones business. I installed it on a dual-booted (XP/Debian) Laptop w/ 512M RAM and after upgrading from 7 to 8 my machine in XP began to lag badly.