Hi, Raider.
It sounds like you bought a MiniDisc player based around recording MP3s for portable use, and that the PC-link gets your song FROM the computer TO your MD player. Heck, this "PC-link" is probably a standard cord, but who knows... This is what I would do:
The best way to transfer sound from your recorder to your PC is by using the headphone OUT on your MZ-R70 into your soundblaster AUX IN (I have one too, I think it's the green 1/8"hole, maybe not). From this point, you should be able to hear your MD (if you play it) through your computer (that is, through whatever your computer uses to amplify itself, whether it be stereo, dedicated speakers, whatever). Once you're able to get sound through your computer, any recording program should be able to record the music for you.
http://www.protools.com has a good free recording program, you may need to hunt it down (it's a version of "ProTools," I'm not sure what it's called, sorry). Anyway, you'll need one of these recorders (or, hell, Windows Media Player will record 2-track (stereo) for that matter, use IT) to record, but make sure beforehand that the headphone output from your MD player is set at a level that doesn't create distortion when it gets in your computer. That is to say, if it sounds "different" from how you're used to hearing your music through headphones, you probably need to turn it down on your player (because it's too "hot" for your soundcard at that point). If you still can't hear the MiniDisc, then double-click on Windows' volume/speaker icon in the taskbar and make sure nothing is muted or turned down. SoundBlasterLive!'s interface is tricky, don't mess with that unless NONE of this works.
If you need to buy a cable to hook up your MD player to the computer, you're looking for a 1/8" male to 1/8" male stereo cord. RadioShack'll have 'em for like $2.99 for a six foot cord. (not sure what a "PCLink" is, btw)
Good Luck!
