This computer is not for consumers, or the average consumer. In case you didn't notice, or didn't check out the link, they are selling computer systems aimed at the video professional. These people work for companies that don't think twice about buying a $20,000 computer. The type of people buying these computers don't care so much about design or video card performance (although why they don't offer it with the 9000 FireGL boggles me) but they do care about hard drive performance (notice the RAID setups) and processing power. Time is money in this business and time saved is money saved.
Now a Dual P4 setup in a laptop isn't for 99% of people out there. But check this out, it's fast and it weighs less than 8 or 9 lbs., easy enough to carry around, but it probably drains too much power to be considered portable. Some configurations come with a battery pack though.