Well, they have about 175 XBox games released. So, let's assume you like all of 'em, and they all take up an average of 5 Gigs. That would equal a whopping 875 Gigabytes worth of HDD space you need. This doesn't include, of course, the full, emulated sets for the various emulators, which would take up, say, 15 Gigabytes, give or take a Gig. Lets tack on another 10 Gigabytes, because if you fill a HDD up to the brim, the games suffer for it. This leaves a grand total of 900GB. 137GB seems real small compared to that, eh?
Of course, this is a pretty innacurate estimate, as most people wont want every single XBox game, and some people may not care enough to get the full sets for the emulated systems (heathens =-). But, hey, just wanted to put my two cents in. Not trying to be a prick or anything, but I'm an obsessive-compulsive collecter: I can't just get some of 'em, I need to get _all_ of 'em.
Toodaloo.