First, go to your Firefox settings by putting "about:config" into the location bar. Click past the warning message, and scroll down to browser.urlbar.maxRichResults. This sets how many recommendations the Awesome Bar will display -- it's 12 by default, but you want to change it to 0.
Change it's value to false by double clicking on it. There, now your 'awesome bar' is a regular URL bar.
"May your future be limited only by your dreams." -- Christa McAuliffe