<p>There are basically three different types of music software you seem to be talking about.</p>
<p>The first records and edits sound waves that are captured by a microphone or pickup. An example of this type is the freeware program Audacity, which will be plenty powerful enough for a beginner.</p>
<p>The second type is called a sequencer and allows you to program your computer to capture, edit and play back data that it collects from an electric keyboard or other MIDI-capable instrument. The playback functions may use sounds produced by the computer, sounds produced by an external instrument or synthesizer, or a combination of all of these. Some sequencers may also have some audio recording and editing features that allow you to combine recorded audio with programmed computer-generated sequences, but are usually not as strong in the audio editing realm as programs specifically designed for that. One commercial version of a sequencer is Cakewalk Pro. A decent free program that would allow you to get your feet wet is Quartz AudioMaster.</p>
<p>The third type is music notation software, which allows you to create, edit and print sheet music. Examples are Finale and Sibelius. Finale comes in several different versions, with increasing price and capability. They offer a 30-day free trial of many of their products and their academic discount prices are pretty good. There are a few freeware music notation programs, but I have not yet found one that I would recommend.</p>