Yes I do this. Your choice! Mac has alwise been ahead in multi meadia end. Now if you were to post this question in the Mac fourm I know what the answer would be. I use both.
I'm not sure why you are worried about feedback?? Or how this enters into what you want to do.
Are you converting voice only or music also?

So lets take the output of a tape player to the line in of the computer. Now you will need recoding software Roxio Easy CD creator PC, Roxio Toast for the Mac as an example. Set the software to record press play on the tape deck. when your done burn the file to a CD.
Expermint with you current PC untill you understand the whole process before you buy new gear.
Hard to say what to charge since any one with a PC can do this. John