Hey there and welcome to the forum.
Basically , even audio cd's are just a bunch of bits and bytes.
So if you could copy those bits and bytes directly to your harddisk and play them , you should have a perfect copy.
However , there is always some margin for error and error correction.
The best thing to do of course is to have a 1 on 1 copy of your audio tracks. A program like Exact Audio Copy can help you with this.
The process of obtaining digital copies of cd or dvd tracks is called "ripping". With this program , you can rip those audio tracks towards your harddisk.
Now comes the tough part. The compression.
Naturally , if you store the sound 1 on 1 , you have no quality loss (except that margin i was typing about) but would result in the biggest filesize per track. Here's where mp3 comes in handy as the most commonly used compression algorithm.
I could give you lots of advice to use 320kpbs , vbr , cbr and a lot other stuff, but i think it's best you experiment with these numbers and compressions.
For sound card there are also two choiches. Do you accept a normal common , but widely recognized audio card such as the soundblaster , or do you prefer an incompatible but high quality soundcard like the Terratec series ?