they are not amplified, so if you wanted to use them with your computer, you'd need an amp.
They'd work with an entertainment system, but they are designed for human voice, not a lot of high frequency response.
I think they were 4Ω and rated up around 5 watts somewhere. Would be good for radio/scanner use, but probably not going to be good for high fidelity music listening.
If you can get them for free, you could probably make a lot of people here happy by giving them away for the cost of shipping.