I don't think they put the rating in their RSS feeds, so it'd be a matter of grabbing the page for every drive. This thing caches the feeds (cache expires after an hour), so it's possible to do the same with the pages (or maybe even do some stuff with a database), but it'd make the initial load a lot slower.
A good idea might be to store the model number for every drive it sees and have a nightly job that grabs the page for every one or something. That's something I can look into after break.
I'd be happy to post the source for this thing if anyone wants to mess around with it.