Take the cassette and clean the tape well connect the output of your tape recorder to the computer using an AV cord. Play the cassette. In computer record the signals from line in using a program like Audacity.
the best is musicmatch jukebox.. i have almost converted 200 of my cassettee using it (for almost 6 months)..
the software suppresses the hiss and humm... and i recommend it sincerely..
Long long long ago i remember using Sonic Soundforge with a Panasonic deck to convert Metallica Load , Garage Inc, and Reload. The setup gave excellent quality.
Those were the days...