Processor speed is no longer the issue, performance is. Performance per watt, performance at clock speed and performance at price.
AMD/ATI has the market cornered in performance per dollar, and the midrange. Intel has a good midrange offereing, holds the performance crown by a small margin, and has a very mediocre low end offereing. nvidia is still overpriced and believe their shit doesnt stink.
Imagine it like this.
Intel i7 is like a Porsche, it costs as much as a porsche, the accessories cost as much as a porsche accessory would and it goes 150MPH but only carries two people.
AMD Pehnom is like a Covette, it only costs as much as a corvette, the accessories are available for cheap and it runs 145MPH
The cell processor is like a bus on crack, it costs as much as a crackhead to support, only wants what it wants and runs 200MPH
ATI/Nvidia GPU's are like the bus strapped on the space shuttle, they are way more expensive, and do way more than just graphics these days.
So, in short. CPU's are slower than either, the cell processor is a costly oddball that no one wants at the family dinner party, and if you believe a graphics card is only for that you need to read up on what has happened int he last three years.
I watch shows on the internet and my ATI card accelerates it, cleans it up, and only uses 3% of its total processing power.