PC Based Audio - How?

I am hearing a lot of good things about PC audio as a replacement for conventional CD players. My question is threefold; first, what are the basic components I need to run a Mac laptop based PC audio system? Secondly, is it possible to simply feed the digital output from a Mac laptop (or MS Windows laptop) into my Krell HTS 7.1 processor for D/A conversion? Finally, any advantage/disadvantage using a laptop over a desktop for CD storage/playback? Any comments on equipment choice (say for a $2k budget), software and file ripping/storage formats would also be appreciated.

Thanks in advance for your advise.

Regards,

Marcus