Managed antivirus services

We are trying a new managed antivirus service. Just about the only one we found is TRVProtect using Trend Micro OfficeScan – has anyone tried this before? We have signed up to it and find it quite cool. You can logon to their Security Center (security-center.trvprotect.com) and check up on all your virus logs and updates from a web application!
Any thoughts?
Roger