Several others have replied that it's probably not worth the effort... I agree. If you want to be really sure you've saved that last bit of info, check the Log file; when it says that it's "Writing local files", your last checkpoint has been written. Then you can shut down and salvage the last few minutes of folding.
Would you, by any chance, have an idea as to why my son's Win XP PC successfully sends the completed work unit and receives a new one, but doesn't start processing it automatically? [I think he said he had to reinstall F@H to get it to start processing the new unit.]
Thanks, I'll do that.