If you used my unroot zip it should have deleted those files.
Boot into Clockwordmod Recovery and then connect your phone to the computer. CWM Recovery will run be seen on ADB with root permissions. Use ADEB commands to delete the two files.
Before issuing the following commands, after your phone is connected, use the menu in CWM Recovery to mount the system. If you don't mount the system you are seeing CWM's mini Android system and not the phone's. Then use the following ADB commands.
#adb shell rm /system/bin/su
#adb shell rm /system/xbin/su
Now use the CWM Recovery menu to unmount the system. Then reboot your phone.
That should do the trick for you.
The other thing I'm worried about is that when I was on 2.2.2 I rooted via SuperOneClick. Then I unrooted, flashed the OTA 2.3.3, and rooted using your root.zip update. I'm worried SuperOneClick may have left some crap behind in bin or xbin that Good For Enterprise may detect. Anything else I should be on the lookout for to delete when I ADB in from CWM? Busybox probably, but I worry there may be other files.