Why not buy a router? Most routers nowadays have built in firewalls. That way it won't take up any resources. Just a note: one thing you do loose with a hardware firewall is the ability to block at the OS application level (meaning you can't tell the firewall to block all traffic from a particular executable.)

I think you have to ask yourself the question: "Will I want to listen to this song in 3 or more years? If I do want to listen in 3 or more years will I want to repurchase the song in the new xyzDRM format that is better-than-128bit-but-still-not-perfect-quality?" If you are the type to discard your music after a few years then I'd go with the pay-to-play walmart option, chances are you're not too concerned about having a collection of quality recordings. However, since you care enough to ask this question, then chances are you have a bit of pride in your CD collection. If thats the case then you should purchase-to-own, that is buy the CD. Then you can rip music with the quality level you desire. Personally I try and rip all my music in a lossless format, with flac using dbPoweramp or sometimes EAC, that way I always have a perfect copy at hand and have a back up if one of my CD's become unreadable. You can always copy from a lossless format like .flac or .ape to a lossy format like .mp3, or more preferably .ogg (if you have a portable player that plays ogg, like my Samsung YP-F1).