Quote from Magna:
It's called SpinRite and you can take a looksee here:
http://www.grc.com/default.htm
I will second that. SpinRite is awesome and has been around since the 80's (obviously it has been upgraded as HD technology has evolved). It can take a looooooooong time to get things corrected, but if it is correctable - SpinRite is your best option for less than $100.