Personally, I don't think Avast is all that great. The last two Storm trojans I found were detected generically by an admirable number of other AVs, but not by Avast. If you have typical corporate users, you'll probably be wanting Storm detected, for one thing 😉
When I had a corporate-type network, we used McAfee's enterprise stuff. ePolicy Orchestrator was nice. The AV client was rather CPU-intensive when all the bells & whistles were in use, and I don't think McAfee's detection rates or update rates are that impressive anymore either. Probably better than Computer Associates, though (and more expensive, I'm sure).
Who else has some recommendations?