Yeah, although you just used a lot more letters than I did.
Your post gave me some ideas. I've been reluctant so far to use disk management, just in case it would take it upon itself to wipe my partition clean if I were to try and add the missing partition back (murphy always has to be watched out for.) I was hoping there was some secret trick to just kick windows in the rear to stop it being irritating and just show me my missing stuff.
However, braving the odds by poking around in disk management I noticed my partition (software-striped across twin 1TB drives purely to make them one bigger logical unit instead of two smaller) said "foreign", with a little drive icon with an exclamation mark on it. Foreign, huh? Hmm... Looking around the interface for anything helpful I find...absolutely farkall. I hate the disk management tool, it's terribly poorly designed. Right-clicking, I got a context menu. "Import foreign volume" (or somesuch) looked like a no-brainer choice.
It brought up a wizard consisting of a whopping ONE step. Click, done. Ok, my 714GB steam library is back. Yay.
Finally, if you've been able to get to the point of assigning a drive letter and doing some file system navigation, are you then running into "access is denied" issues where you have no ability to reassign the permissions?
Weirdly enough, no... From what I can remember, I've always been tripped up by "access denied" issues those few times when moving drives from one windows machine to another (but as I recall, not when nuking the OS on the SAME machine and re-installing a new OS on it.) I've had to claim ownership of everything on the drive and then things have been fine, but this time...nothing, from what I can tell. Weird. *shrug*
In any case, problem solved. Thanks a lot.