URL rewriting to create something like www.myspace.com/username based on a userID query string

I think I did a good job cramming everything into the subject :) but to elaborate: I'm looking for a thorough tutorial or specific advice on how I can create a system that will rewrite the following url www.website.com/roller828 into www.website.com/Default2.aspx?viewUserID=14 behind the scenes in order to use the userID to populate the profile information on the page. If you haven't made the connection yet, roller828's userID in the database is 14, and what I want to happen is when Default2.aspx is loaded, roller828's profile information will be displayed on that page. My main problem is that I find tons of tutorials on so-called dynamic URL rewriting, but I can't find anything that will take in a username for a parameter and communicate to the sql database to grab the userID for that username and rewrite it into the new URL (or that will allow my server side co ...