I've used headphone out jack of a receiver/amp unit with success.

Cassette deck connected regular fashion to receiver amp and using headphone out jack of receiver amp.

Reason: I've noticed a lot of stereo cassettes have differing bias between left and right and sometimes between A side and B side of cassette. The receiver has settings that let me adjust for these differrences (The differences show up as you observe the signal on your PC audio software).

I try to move the units close enough so that I can use a short cord, although in theory if you have a good shielded cable it shouldn't matter. (I wouldn't run a vacuum cleaner near the cord at the same time as I was recording, though!). Typical headpone out jack is regular. Typical line in to your computer soundcard is a mini. What works well is a jack adaptor to a mini, and a mini jack to minijack patch cord. If you have to buy one make sure it is stereo, my supplier had a lot of cords not all clearly marked.

Pay attention to whether or not the cassette is pre-recorded Dolby.