Like most freeware websites it is inundate with ads for products that do the same thing, but you have to to pay for them. Quick Media Converter is free.
Link to website: http://www.cocoonsoftware.com/
Link to the direct install: http://www.cocoonsoftware.com/download/INSTALL.zip
As a free bonus the Microsoft Reps informed us of this handy site that installs a Codec package on your machine. It even allows .mp4 to play in Windows Media Player and if you are running Vista it will allow you to edit .mp4 in Windows Movie Maker. I have found this to be extremely helpful.