but im sure there will be lots of changes in the final build than the 7600build....
I don’t think so, RTM is sent to OEM system builders like DELL, HP, Lenovo etc. to do their customizations, bundle drivers and software to release preinstalled on their machines. Therefore nothing significant will change.
Maybe small things like additional themes, wallpapers and minor software updates will be included in the final retail release, but the core OS files and the build number will remain the same.
If you look at the previous MS OS build numbers you'll see that they are all nice round numbers i.e : XP : 5.1.2600, Vista : 6.0.6000 and by the looks of it 6.1.7600 seems like a nice build number for the final version.