In my opinion, it is important to understand what type of recording you are going to perform on your PC because with a computer you can record either MIDI signals or audio signals.
MIDI signal is a standard adopted around the early '80s which consists (without getting too technical) in allowing computers, MIDI keyboards, or anything that adheres to this standard to communicate. By using a universal protocol, you can connect multiple keyboards in "daisy chain" and have them communicate with a MIDI sound generator or a computer.
A very important thing to know is that the MIDI signal has no sound itself; therefore, to hear a MIDI sound, it must be assigned to a sound generator, and here the quality of the sound generator matters.
If you have a MIDI track and connect it to a sound generator like the one in Windows, you will get quite nasty sounds, whereas if you connect it to a sound generator like a sampler, the quality is obviously much closer to being realistic.
The convenience of MIDI is its versatility and its low "weight"; in fact, a long track only weighs a few Kbytes.
(Briefly stated) the MIDI signal contains information regarding: note, note duration, volume-attack of the note, and decay... as well as the type of sound that was intended to be assigned, for example a piano, a violin, or a drum kit, etc.
Audio files are another story; they can be analog or digital. The former is, for example, what you play through old cassette tapes or vinyl records... the latter is the digital file... what you play via CD.
The PC uses digital signals to play back or to record, so it converts all sounds into numbers on a binary basis (0 1, indeed "digit" as in digital).
A CD audio file is composed of a sampling frequency of 16 bits and 44.1 KHz; therefore, when we play an audio CD, we are playing a format called Wave, which weighs about 10 Mb per minute.
Another format is MP3, which eliminates those frequencies that are not audible to the human ear, making it "lighter." MP3s can have different types of frequencies; however, on average, an MP3 file weighs about 1 Mb per minute (a significant saving).
Now you must understand what you are recording on the computer: MIDI signals or audio signals.
A dedicated sound card is important; in fact, using the integrated motherboard sound card is not very convenient, which is why the sound coming out isn't the best. There could be problems with crackling sounds or hearing pops (which is a driver problem), or hearing the sound with background hiss (which is a problem with the Analog-to-Digital converter located on your motherboard's sound card).