The typical symptoms that a disk is about to fail -
- accessing anything on a disk takes a very long time or return with errors
- mouse / keyboard becomes very jittery when trying to access files on the disk
If you don't mind trying, how about going to DOS from Windows? ;) Since you've got that in an enclosure and connected to another machine. To get to DOS its Start -> Run -> "CMD" and enter.
You could try going to the broken drive and see if you can copy files that way perhaps?