In our office I have deployed the following AV protection:
29 win98 PCs w/ internet access, but not email:
McAffee VirusScan
1 winXP laptop w/ internat and pop3 email
Norton Internet Security w/ NAV and personal firewall
9 win2000 PCs w/ internet access & pop3 email (Outlook Express & Outlook)
Norton Systemworks 2003 w/ NAV 2003
2 win2000/NT servers internet access, no email
Symantec Small Business 8.0 Corporate Edition (for Servers & PCs).
I've had some problems with email viruses not detected using Mcafee, so I switched all email users to NAV (Systemworks). Most of our internet users are browsers, so our infections were mostly Melissa style emails, and the ocassional virus hoax alert. Since switching to NAV (past year) we haven't had any problems, and Systemworks has other perks (Ghost, Disk utils, Reg clean, etc).
We probablly encounter 1-2 virus infected emails each week. NAV catches the emails before the user is able to open the infected attachements, etc...
I recently deployed Symantec AV on our servers (this week), and plan to eventually migrate all of my win98 PCs to Symantec as well (to take advantage of virus definition deployment and alert methods.
Firewall:
We haven't yet been hacked, but are using Linksys Router with IP forwarding (only pcAnywhere and Terminal Server currently fwd), but I will start to worry more with up-coming deployment of Exchange Server and remote access of email.
I'd also like to find a cheap copy of Symantec Antivirus with Exchange filtering if possible.