Are you going to use the computer to record instruments or to make the actual music (drum computer, synthesizer, etc), or both. This makes quite a difference as to the equipment you'll need.
For example, a keyboard doesn't need to be 'recorded' using a microphone, because it can send what you're playing into the computer as MIDI data. The computer transforms that data into sound. You won't need a microphone in order to do that.
If you want to record vocals, guitars or other instruments, that's a very different ballgame.