Recording "Outside" Sound
If you plan to use Reason with a typical sound card and want to use your computer to record stereo sound that can be imported into Reason, you will need additional recording software.
The good news is that a lot of programs will record audio and allow you to edit it. They're called audio editing programs. Many are shareware and freeware; check the Internet. And there are many inexpensive commercial audio editors that are easy to use. For Windows, Cool Edit, Audacity, Audio Blast, Soliton II, and Encounter 2000; for Macintosh, Amadeus II, Audacity, Jasmine, D-Sound Pro, and GarageBandjust to name a few.
What you will need for multi-track recording
If you do want to record more than one stereo input at a time, you'll need to purchase a "hardware (or "audio") interface, and a multi-track recording program.
An audio interface is an audio input box (like the four-input MBox for the Mac) that converts incoming audio signals (such as those from a microphone or guitar cord) to digital signals and then writes them onto your hard drive.
To play back and mix together multiple music tracks of recorded audio, or to record more than one stereo track at a time, you'll need another program. Pro Tools, Cubase (Mac/Win), GarageBand (Mac), Digital Performer (Mac/Win), Nuendo (Win), and Sonar Live! are just a few designed for this task. A multi-track recorder isn't cheap, but it's well worth the investment if you're serious about live recording.