Well it seems the drive is knackered from just past LBA 300,000,000. There's some issues before that though, including block 0 and a clump around 199,000,000.
There's some bad blocks but most of the problems appear to be blocks/sectors that take longer than 50ms to read.
I wonder if it's possible to mark the bad blocks as unusable and still use the rest of the drive?
I've probably got most of the games on my backup drive already but is there a way to copy the files from the dodgy drive into appropriately named folders, i.e. I keep the games backed up in folders like CODMW3\5445378 so that I know which folder is for which game. I can obviously copy the folders from the drive as is but then I'll just have folders named 5445378 which isn't that useful when I want to find a game to copy to the drive, so is there a program that will create human-readable folder names and copy the files to those?
I'm going to connect the drive directly to the motherboard rather than via the e-SATA enclosure and scan it again though, just in case the enclosure is causing problems.