Musjunk, i'd have to agree with your friend. Celerons are basically hacked-up versions of Pentiums, with smaller caches and generally decreased performance in order to cut costs and energy consumption. They're meant to be more economical, but the cost to performance is still not worth what you pay for, for a socket 478 processor.
Intel Celerons, AMD Durons, and video cards with the 'SE' label are just cheaper, poorly made products meant to lure in people who only look at clock speed and brand names.