Virus scanner for mail and file servers

I have to set up a virus scanner for a mail server and two file servers. The candidates are Clam AV, McAfee, Trend Micro and, to a lesser extent, Kaspersky. Not because I'd prefer any of those but because the first three are the only ones that are officially supported by one of the products we will be using.

Now I'd like to avoid McAfee. My personal favorite would be Kaspersky because of those candidates I know it best.

My questions:
How do Clam and Trend Micro compare to Kaspersky? Which of those three would you use and why?
Is the mail/file server version of McAfee as shitty as the one for workstations?

Leave virus scanning up to the clients. Your mail and file servers should be running some variety of Unix anyway, and as such be immune to Windows viruses.

>>2
Good point, the servers are running on Unix and thus largely immune.

But we already have Kaspersky running on the few Windows clients we serve. The point of this is to add another layer of security for the Windows clients and a first one for the Unix clients, just to be extra safe. Which is another reason why running Kaspersky on the servers as well wouldn't be optimal.

another layer of security for the Windows clients
Lost cause.

You better have CPU Power be hide that Unix Server, because installing a AV on a Mail Server will eat CPU Power and slow down Hard Drive Speeds. If you really need a AV I would say CA ETrust or Clam AV for the Unix Server.

Besides protecting a Windows Box is sometimes hard, just lock everything down in the AD so the clients cannot install crap or do anything - LoL.

clam would eat the less CPU power and slow the HD less.

is this extra layer really that important? who are you pissing off so much that you need to go to such lengths?

>>5
The servers have 4 Xeons, 3GHz each. The primary mail storage is on a RAID1+0 consisting of 15k rpm SCSI discs. We planned ahead and I hope the performance will be adequate.

>>6
Well, it's not that important. but the mail server software offers the ability to integrate a scanner on the service router level, so I thought why not use that ability?

Since both of you suggested Clam AV, I will do some research into that one. Thanks.

>>5
>just lock everything down in the AD

God damn, I'd fucking love to do that. The problem is, the people we serve are doing software engineering, testing and support. They need to be able to screw around with the systems. Shit sucks.