You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
ValveTime.co.uk | Valve News, Forums, Steam
This actually happened by accident, skipping the details, pop in your favorite music cd, ie rage, korn, whatever, then open up hl2 and play a level. There are files which define which track plays for which level. Maybe not original, but cool huh?