Another option is this thing...
...from thinkgeek.com.
BTW, the tapes are copyrighted material so I wouldn't recomend posting them on your site. I appreciate the offer though...
I know what software i'll need in Linux. I also have an audio-in jack on my computer which would be straight forward to use with a cassette recorder. The thing is the number of tapes to convert. There are 20 total sets of 6 hours a piece and swaping out one tape at a time it will be tedious. I'm not even sure that it'll be worth it yet. I may just listen in my car.