I deal with audio production, and wouldnt look past Adobie Audition my self, it supports almost all audio formats under the sun and has a lot of great features.
Other good ones to look out for are: Wave Lab, Goldwave & Soundforge.
Go to this link for a list of many others:
http://www.sonicspot.com/sampleeditors.html
To transfer your cassette tapes onto cd, you will need to record them out of your amp via line out, typically RCA's (if thats what you are using) into your line in (back of your sound card)
Keep in mind thou it all depends on your sound card how good the output quality will be when you record your work.
For proffesional results, you want a card with atleast 24-bit resolution & 48khz, however if your recording from an analog cassette tape, the quality would allready be de-grated so even a cheap audio card if not even 'on-board' audio on your motherboard will do the job too.
Hope that helps.