There are various antivirus products available from the likes of Symantec,
McAfee, Trend Micro, Grisoft, etc that work on servers. You can visit their
websites for versions and prices. As far as firewall it depends on if you
want software or hardware firewall. If you can go with Windows 2003 Server
it has a built in ICF firewall like XP does. If you want a hardware
firewall, depending on your needs you might be able to use something like a
Netgear ProSafe firewall starting at under $100 and the sky is the limit
from there. Firewalls from companies like Sonicwall and Netscreen would have
much more advanced logging and more configurable firewall rules including
managing of outbound rules. Those brands can be purchased from under $200
used on Ebay for basic unit that allows ten outbound IP addresses. If you
buy used, be sure to check out the firmware installed to make sure it is
fairly recent as many of those companies do not provide free firmware
upgrades. --- Steve