Well, I can get line-in to work, and I'm truly tech-challenged. ATM I'm slowly getting my old premixed cassette tapes onto my harddrive, then copying to CD (these were tapes I made when I taught aerobics so they're kind of special to me). I simply put one end of the plug in the headphone jack, the other in line-in, fire up Audacity, hit play on the boombox and record on Audacity.
If it works with a bitty boombox and cassettes, it should work with just about anything, I would think.
Streaming music? If that's coming from a site that shows video (like Roadrunner used to), as far as I know there is no way to save that to your harddrive. I could be wrong, but I never found a way to do that. I think it's made close to impossible so you have to buy the music via an online music store.
Can it only work on things like CDs or can it record from streaming music too?