you haven't mentioned what kind of server it is? Windows or Linux?
If you haven't decided a solution yet, I would like you point to Linux based solution because its cost effective,flexible and more secure. in servers, Linux really shines. not to forget, its immune to all window's based malware
you can install
centOS distro and use the following tools
* AV:
ClamAV
* Firewall: iptables with some fancy frontend like
APF or
csf
* Networking & filesharing: Samba
*
SQUID: Web caching to speed up internet access and reduce bandwidth usage. and can also used as filtering and monitoring web access.
What great is samba also supports
Active Directory integration.
Doing this, you will end up saving you lot of money purchasing licenses for proprietary software.