You'll need to get a cord to run between the headphone jack of any cassette player (or boombox), then get a program called Goldwave at www.goldwave.com Goldwave records the incoming source in realtime. Just hit play for the cassette and click record on Goldwave and you're set.
Goldwave saves files as .wav's, so you'll need to get a .wav to .mp3 converter. Best converter I've seen and used is here: http://www.americanshareware.com/
Goldwave saves files as .wav's, so you'll need to get a .wav to .mp3 converter. Best converter I've seen and used is here: http://www.americanshareware.com/