Eugene's observations

When you suspect that your disk has failed, the following exercisers will test it for you. Click the link to the manufacturer of your disk and you will be take to a place from which you may download a test program. Typically this would be used to create a bootable disk from which you would start the failing PC.

Hitachi
Maxtor
Samsung
Seagate
Western Digital
Fujitsu

A link to a similar list is http://www.tacktech.com/display.cfm?ttid=287

You can find the manufacturer's ID by looking at the disk, but if you are too lazy to pull it from the case, in Device Manager, click on the + to the left of "Disk Drives", then right click on the name of the drive|Properties|Details tab|click the down arrow to choose "Hardware Id's". Copy the VEN and DEV info from there and enter into http://www.pcidatabase.com/