"Part two" is to get a second HD so that I can swap between them for Time Machine. Once Ghidorah1 (the one in use now) fills up, I trade in the other drive. When it fills up, erase Ghidorah1 and switch it in. That way, I don't have to worry about trying to delete to make space on the active drive, plus if either drive fails catastrophically I have at worst a relatively recent image on the other drive.
Ghidorah1 is 320G, and the initial run of Time Machine took 55G, so given the default "fresh full run every month" setting I should have at least a couple of months before I need Ghidorah2. 320G is fine, I'm looking for a good price on a decent quality second drive, but since I know nothing about HDs I figured I'd solicit advice on brands to seek or avoid, and if anyone knew any good deals out there right now. (I do watch Woot, but they tend to have internal HDs, and once you factor in the cost of a housing the bargain isn't so good anymore.) Slender is good, too, I've got Ghidorah1 tucked away between two things, it's not much more than a centimeter thick.