The software sites have posted a mid 2007 MacBook software update, but it doesn't show up as needed when I try Software Update. Is that an indication that I don't need it and is there a list somewhere of serial numbers that need the update?
versiontracker, macupdate, apple.com for example. The update is about HFS+ Journaled. Apple has "forgotten" to turn on Journaling on the most recent MacBooks (and MacBook Pros). The update basically turns on Journaling and instructs you to boot from the installation DVD to repair the volume.
AFAIK it _should_ be in Software Update if needed (I don't have an affected machine), but you can download the update (and read about it) here:
Well on the downloads sites (MacUpdate and VersionTracker) they talk about it just turns on Journaling in the hard disk and it only affects "MacBook (Mid 2007) or MacBook Pro (2.2/2.4 GHz 15-inch)". Does you Mac fit into either of these categories?