I'm kind of confused about the topic here. Are you wanting to build a system used to record and produce audio, or do you have an existing PC and want the equipment necessary to record and produce audio?
existing equipment is PEAVEY XR 800F 9channel console which currently connects to cassette recorder via 2 white line ins and 2 red line outs
Gotcha. So it looks like that mixer has a "Tape Out" that you're probably running into your cassette recorder. I don't know what your price range is, but what you're going want is something like this: (http/www.amazon.com/TEAC-CD-RW890-Recorder-Remote-Black/dp/B0045EJZRQ/ref=sr_1_1?s=electronics&ie=UTF8&qid=1378165387&sr=1-1&keywords=TEAC+CD-RW890+CD)
This will allow you to plug your RCA (white and red cables) from your mixer into the recorder. What is your price range? They're not super cheap, but this might be the way you want to go.