Symantec vs. Trend Micro

Hi,
We use from 5 years now the Symantec Antivirus Corporate Edition. At this time, no viruses infected our network.
A headquarter decision asks us to migrate to Trend Micro Antivirus because of the company standard. Until now, I did not use Trend Micro Antivirus.

Our environment:
-Win2k domain
-Win2k, WinNT40 servers
-WinNT40, Win2k, WinXP workstations
-Linux Internet servers ? firewall, email, web, etc.
-Citrix, OfficeXP, SAP, VERITAS backup, etc.
-soon an Exchange server

Please share your impressions/experience/recommendations
about these two products.

Thank you,
Florinel