All you need on hardware is a stereo audio cable from the audio or speaker output of your casette recorder (or any other audio source) to the aux input of your sound card. Such cables are available at many computer and electronics shop.
Activate the aux input with the audio configuration soft that comes with the sound card, also activate the speakers to allow you to monitor the recording with them or with earphones.
I use the excellent Diamond Cut software (downloadable from Info@tracertek.com)to record to the hard drive and to edit it for the removel of continious background, tape and recorder noise. Be shure to cut the recordings into the individual objects so you can address each of them seperately on the CD. Then I use the Roxio Easy CD Software to burn the CDs and print the labels, but there are many other good ones.
I recorded hundreds of reel tape hours, many casettes as well as my LP collection to CDs, it works!
Good luck, Beat.