Re: Novice to live sound recording seeking advice.
Live recording can be very simple, or very complicated depending on your preference, budget, goals, etc.
At the simple end of the spectrum, a portable all-in-one stereo unit like the Zoom H4n that Rob mentioned would be hard to beat (though I have no personal experience with 'em)
Slightly more complicated, but still very simple: a stereo pair of mics into a computer, as you described. Use the highest-quality condenser mics you can find. The results depend a lot on the position of your mics relative to ALL the sound sources, including reinforcement through a PA, audience noise, air-handling equip, etc. (I'll never forget one room-mic recording of my own band that I made with the mics below a ceiling fan. The entire recording sounded as though a helicopter was approaching.) I'm assuming your 'local folk artists' are playing acoustic instruments, in which case I'd try to get the mics as close to them as possible without spotlighting any individual. Unless you're in a very good sounding room, try to maximize your ratio of direct-to-reflected sound.
With only a stereo pair, you have no control of the 'mix'. If it sounds great and is well balanced in the room, this may not be a problem.
If the performers are mic'd and reinforced in the room, you could also record the mixer's main outputs. The board mix will be much more 'preset', while the room mics will be more 'ambient' (depending on how much 'verb or other effects the mixerperson uses). Blend to taste. You'll probably want to delay the board mix to compensate for the arrival time differences between the direct mics (placed inches from their sources) and your room mics (many feet from the source). In small to moderate sized venues where acoustic stage volume isn't negligible compared to the PA's output, the board mix will be very different from the sound in the room. This can be pretty drastic with loud drums and guitar amps, for example, but may not be much of an issue in a more intimate folk music setting. If the acoustic volume of the sources in the room is insignificant compared to the PA's output, and the mix is good in it's own right, then a board mix by itself may be all you need.
If you want to get fancy, you could use a multi-channel interface to take each channel's direct out from the board. This gives you the most control of the mix after-the-fact, but can be complex to set up. And then you have to mix it down, which takes time. If you go this route, and trust the house engineer, consider taking sub-mixes of some groups of channels (e.g. drum-set, background vocals) rather than taking every single channel; it will reduce the load on your computer (assuming that's what you're using) and simplify mix-down.
