Before I build a rig, I'm thinking of beginning mining with simply using the single card on a gaming computer.
If I had to choose would I be better off with an AMD FX 580 4GB or a Nvidia GTX 1060 3GB
I hear that AMD are slightly more efficient at mining but are more prone to overheating which isn't good.
Also, could I still use the computer for light tasks like talking to people on facebook or internet surfing while mining?
I think you mean to say about the RX 580 card. This is one of the best to choose for altcoin mining with the GPU rig. If you want to mine with your computer means also it will work but the profit expectation will not fulfilled like a rig you are using to mine. Currently I am mining with the 5 RX 470 cards for ethereum. It is giving me around 350 USD per month including electricity charge. So choose the right rig set up if you want to be involved in the mining platform.
Yes I did mean to say RX thanks. I guess I'm just nervous about going all in just yet as I never have mined before and I want a new desktop computer anyway, so I figured that would be a good place to start.