i spoke too soon. the drive is not reading at all. i should have taken the data off while i had the chance.
the c: partition is designed to be throwaway. there are two smaller partitions that are not. one is an install partition with reinstall scripts. the other is a temporary partition that currently holds all of my temporary recording material.
i think i can reconstruct the last one, although it will be a lot of work. that's the most important, by far. i can't reinstall the machine as it is without the second, but i can get around that.
it could conceivably cost me a month. so i'm hoping i can get the data off somehow.
lesson learned: a chkdsk may stop a hard drive from whirring, but it doesn't mean it's fixed it. and i should have worried about it.
grargh.
so, i'm going quiet here *again* for the foreseeable future. *sigh*.