Version differences in Office 2003 Compatability Pack   

A few months back I downloaded and installed across our network the 
Office2007 CP, by using Add/Remove progs. and the "Click for more info" link, 
I found that the version was 12.0.4518.1014. This all comes about due to a 
security bulletin in which O2007CP was involved. Due to that, I checked to 
see if the current download had be upgraded. Sure enough, the date and size 
were different. I tried to do a straight update but it fusses and wants me to 
uninstall the old version first. I do so and try again, this time it installs 
fine. Add/Remove now says the version is 12.0.6021.5000.
What got changed? 
There is no ‘Version History” on the download page.
I need to know to determine if I need to make a special update for 500 
systems.
If the update added functionality, I can pass.
If it was a security update, then I’ve got to deal with it.

Thanks in advance
BobT

date: Tue, 2 Oct 2007 11:46:01 -0700   author:   BobT