Fortunately, for people who don't enjoy playing Russian Roulette with their iTunes library transfers (and don't want to buy the software for it), here's a quick and easy guide to how to transfer everything over properly, and make sure that all the little hooks and crannies line up correctly in the new installation -- specifically, iTunes keeps an XML file that tracks where everything is, and you've got to change paths (using a quick find and replace) on all the tracks in your library. iTunes will then use that XML file to backup its own records, and then you're hunky dory.
What I can't find, according to this guide, is what damage I may have caused to my system by just hauling everything in and starting up iTunes -- I checked the Location key on both my new Mac and the old one, and the Locations are completely different, without me ever changing them. Either way, even though I throw around my libraries with abandon (look Ma, no backup!), you'd probably much rather be safe than sorry.