if you are a mac user i have three programs i can't live without. these three are Logic Pro 9, Cubase 6 & believe it or not garageband. garageband is a perfect way to start learning the basic of audio and midi recording with its easy to use straight forward functions. Cubase i recommend being a intermediate program. although it is more intense then garageband and has amazing recording capability is just doesn't compare to the beauty of logic. Logic is by far my favorite recording program but it is very pricey and you need to know what your doing to be able to properly use this program.
For windows users. when i used to use windows i only ever used three programs Fruity loops, Mixcraft & Cubase. Windows is definitly not my favorite os for audio recording but i am a fan of fruity loops thats how i got started. although it is not very easy to use it is a very good beat making program and midi program, i DO NOT recommend it for audio recording. I was also a huge fan of mixcraft,before i got my macbook pro, because it is basicly a garageband knock off for windows and runs quite well. Of course i end on cubase for windows i was never a fan of reason if your wondering why i didn't mention it but i definitly like cubase. its the only program that is identical on mac and on windows which makes it easy for me to transfer files from my mac to my windows.
What program do you use?