You might point out that the really big websites
are all built almost entirely on open source platforms (ebay being perhaps the exception).
Google, (I think) Yahoo, and Amazon are acres of linux servers running custom software developed with free languages and libraries. You can't buy that kind of reliability off the shelf, but you can put it together using various bits of free stuff.
"Whenever you find you are on the side of the majority, it is time to pause and reflect" --Mark Twain
"The significant problems we face cannot be solved at the same level of thinking we were at when we created them." --Albert Einstein
"This is still a dangerous world. It's a world of madmen and uncertainty and potential mental losses." --George W. Bush