We are still running XP machines, but:
1) Are you deploying Patch5 via ePO task?
2) Do you have Global Updating enabled for patches VSE8.7i?
3) From the 7 machine get/post the update.log file (C:\Program Data\McAfee\DesktopProtection
Yes, we are using ePO to roll out patch5, all machines successful updated the patch except those machines running Windows 7.
This could be because ePO doesn't recognise Windows 7 as a supported OS. Before anything else, make sure you have checked in the extensions that are in the Patch 5 package - this may solve the problem.
I've check in the patch 5 extension or else other O/S won't be able to update to patch5, actually I already deploy patch 4 via ePO few month back and all the machines working fine.