We’ve had an enterprise license for Trend Micro Internet Security at our offices for the last couple years. Here’s what I think about IS 2007:
After you’re through disabling the “features” that are unneeded/redundant (personal firewall, wifi monitor, etc.), the versions are almost identical. There’s a new rootkit entry in the anti-spyware section that looks nice if it works, but the spam filtering is still mediocre. Slightly new UI, but it doesn’t seem to be too greedy with system resources. I don’t see any harm in taking TM up on their free upgrade offer.