Life's Rulebook: Cheap, Easy, Best -- if you're lucky, you'll get 2 of the three
The cheapest way is with a headphone-plug to 2 x RCA plug splitter cable - hook that to the playback output of your cassette deck or the record out of your receiver, and then into the Line In jack on your iBook.
Use GarageBand if you have it or the free
Audacity program to capture the audio to AIFF files.
Use iTunes to import those AIFF files, make a playlist out of them, and then burn a CD