I would not bother converting pre-recorded cassettes (movie songs) etc. since MP3s, good quality CDs, youtube etc. are available for me to enjoy.
My need to convert a few Hi-Fi tapes to digital arises because my mother had sung and recorded many devotional songs/stotras on tapes. These are purely vocal w/ out acompaniment and recorded in mono, so loss of quality does not become an issue. The quality vocals in a mono track does not diminish drastically - hardly noticeable.
The conversion process has 3 steps -
1) Audio capture - Capture the audio from the tapes and store it on the computer in digital format
2) Editing/clean-up - If necessary. I use
GoldWave - Audio Software which allows me to remove unwanted sounds, silence, tape hiss etc from the audio tape. Speed up a couple of songs which were very slow. Increase/decrease the vol of the song (songs were recorded at different times, even on different days and hence the input volume is not always constant). The s/w is very powerful and allows you to do quite a lot as far as editing goes.
Split the tape in to different tracks so that the CD you burn will not be just one long track!
3) CD burning - I haven't done this yet.
This is what I'm doing:
1) Playing back on a Sony boombox.
2) Connecting the 'headphones' of the boombox to the audio card 'in' using a audio cable (You can buy one at radioshack. This would be
male-male cable)
3) I capture the audio and store it on my computer in .wav format using the built in s/w tool that came w/ my audio card. The .wav files are very big, btw.
4) I've stripped the 'raw audio feed' that I captured in to different tracks, "cleaned" them and am storing them in digital format.
5) Next, I'll be burning CDs and making copies.
Googling the keywords - audio, cassette, digital, conversion etc. will give you many results w/ touting many s/w, solns and tutorials.
Most editing s/w provide downloadable trial versions and refunds. I tried and soon tired of MS-Digital Media and returned it - all online.
Good luck w/ your project.