Recomendation Antiviurus for Windows 2008 server

I would go with Microsoft Security Essentials. It is free and works great. You can throttle CPU during scans and the active monitoring protection is very light weight and does not cause performance issues. There are no ads asking you to upgrade to a paid service and in several tests I have run using zero day vulnerabilities it has always caught them.

http://windows.microsoft.com/en-US/windows/products/security-essentials

Avast! would be my choice

I use trend micro worry free business, to support 120 systems, its an easy to use console, and easy to manage.  I think they might even have a special for buy a 2 year get the 3rd year free etc (they usually have something like that).  It also has URL filtering so you can setup scheduled times to block facebook, youtube, etc (if you so choose).  

Among other good ones ESET is pretty good, it also monitors windows updates but I found the management console a little confusing at first.

I like trend micro and ESET for they run light and dont hamper the systems performance.  If you go with trend micro by chance I would disabled the smart scan for when it comes to large files it wants to scan them each time which will bog a system down (like a large quickbooks file etc.)

Microsoft Security Essentials is free for business use for up to 10 PCs and is a good, lightweight solution.  Unfortunately it cannot be installed on any server OS.

On the other hand, a lot of people don't run any AV on their servers - if no users are on them browsing t'internets, downloading cracks, opening attachments etc, then there isn't really an infection vector for malware.  If you go down that route then you can run MSE on the clients and nothing on the workstation, for a total outlay of £0!

If you prefer the (illusory) reassurance of a commercial product, ESET NOD32 AV is quite well regarded and modestly priced.  Just don't forget to configure the server exclusions!

Symantec Endpoint would be massively overkill for 7 machines, no?