The level from a standard tape deck is line level. A cable with an RCA pair on one side and a 1/8" stereo miniplug is all you need if you have a standard consumer soundcard or sound hardware built in to the motherboard. Oh, and some recording software.
P.S. If ridl is not a username that's a urban respelling of "riddle," and is perhaps your last name, by any chance are you related to the terrific jazz pianist James Ridl?