<p>I'm looking for a free winforms component for an application I'm writing. I basicly need a textbox that contains line numbers in a side column. Being able to tabulate data within it would be a major plus too.</p>

<p>Does anyone know of a premade component that could do this?</p>

Take a look at the
SharpDevelop
C# compiler/IDE source code. They have a sophisticated text box with line numbers. You could look at the source, figure out what they're doing, and then implement it yourself.
Here's a sample of what I'm referencing:
alt text http://community.sharpdevelop.net/photos/mattward/images/original/FeatureTourQuickClassBrowser.aspx