I recently got a new RBMP to replace my older 15" MBP. I use it mostly as a desktop and the boot drive is ext. Right now it has 10.7.4, but it's a different build than the one that ships w/ the RMBP. I'm new to the whole "recovery partition" idea, so do I just need to boot up from it and then update my existing ext. hard drive w/ 10.7.4 from there or is it going to give me one of those ugly messages telling my I already have 10.7.4 installed and not let me do anything?