Analogue audio from line-out to USB?

How is it possible to connect an analogue audio line-out port direct to
a USB port to capture the analogue audio output from say a taperecorder
with a laptop please? I have a number (actually 100s) of cassette tapes
to digitise onto CDs for archival purposes. I guess that I need some
kind of digitising s/w but don't want to use MS Media Recorder (or
whatever) because I want to be able to play the resulting CDs on a CD /
DVD player and most of these wont play WMA or WMV formats. Any advice
would be appreciated please. Many thanks - CJB.