Server-Client Anti(virus/spy) for business, what's your fav?

I'm currently 'playing' IT here at my company. We have a fairly nice server running Win 2003 Server. It runs our exchange server, DHCP, domain login, and the like. Expands out to about 20-30 computers around the office/labs which benefit from any server-type programs we could ever need.

When I got here, Symantec was installed on all of the computers as well as the server. I personally dislike Symantec, but that's beside the point. Symantec was also interfering with many applications we use in the lab. Office computers, are given internet privileges, while lab computers are blocked from the internet (they can still receive email through our exchange server if they have a login). I took all the internet based computers and I went with AVG 7.5 so they could work on their own. Unfortunately, I'm now regretting it with AVG 8.0, now taking care of things, it's a nightmare.

I'd like to get all the computers back on client-based security where the server sends updates to the clients. The obvious question is, what program is really going to work the best? I want something really light that's virtually invisible to the users (it just does its job without asking the user what he wants to do). Basic spyware/antivirus, scans at night, etc.

ive always been a fan of nod32

We use mcafee v8.5Ent and are happy with it. Have an EPO server setup to push out patches/updates daily.

For email scanning, we use trends micro scanmail for exchange. Scans the mail in realtime.

Our Spyware/malware is handled on our firewall.

Heh, we used symantec at my old job as well. Worked fine for us, but it was a pretty simple setup.

My dept has been using McAfee 8.5 Enterprise as well. It's in par with NOD32 as far as its ability to not bother you ever about crap. I was surprised considering how annoying the consumer versions of McAfee are.

For a business setting I suggest you look into F-Prot. I'm not sure if their pricing scheme is the same, but back when I did small business consulting, a 10 license agreement was like $50 per year, and the results were very very good. (And they have higher volume agreements as well, for larger places.)

And those 10/x licenses didn't have to be restricted to the business premises. If you had an office with 5 machines, you could use the remaining 5 keys at home.