You will need a soundcard. What kind of soundcard depends on what you are trying to achieve. A card just for midi will only work if all of your recording is done with machines like drum machines and keyboards. If you are wanting to record live instruments like guitars and vocals, midi is useless.
Do you have a soundcard on your pc already? If so, then if you are just starting out then you can use that soundcard. Look at the back of your pc for the outputs and inputs to your soundcard. There should be one input for a microphone and at least one called "line in". Only use the line input. If you want to record two tracks at a time, then you will need a Y cable which will keep the signal separate even if it's going to one input (these cables are specifically for stereo applications and have a ring on the tip of the jack).
However, you are probably not going to get the greatest sound out of the pc, which will be due to the fact that the soundcards that come with computers are not designed for anything other than the most basic consumer audio applications.
If you do not have a soundcard, or want to upgrade to a better one, then you need to figure out what your needs are. If you are the only one recording, and you want the pc to be the main interface you use for mixing and burning to cd, then you want a soundcard with two inputs and two outputs.
If you want to use any external processing to the individual tracks after recording then you will need a soundcard with at least two inputs and as many outputs as you think will be necessary. Most available are soundcards with two inputs and six to eight outputs.
If you want to record many instruments at once, like drums, bass, and vocals, you can either get a mixer and mix the entire thing down to two inputs of a soundcard, or get a soundcard with six to eight inputs, and either two outputs, or multiple outputs as described above.
Once you figure out what you need, then shop around. Some popular soundcards are Lynx, Echo, M Audio, and MOTU. Narrow it down, and do a search on this bbs for those products to determine what the best soundcard would be for you.
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