I'd say it's hardly fair to compare a refurbished machine to a new machine. If you take a new model of the 08 machine from the discontinued section, its only $100 difference between them. The tradeoffs being .14Ghz and a more dedicated video card with the old model vs. 2GB of faster RAM and a 640GB Hard disk (320 bigger). So its a matter of which is more worth your money.
EDIT: Interestingly, the tests were done with all 24" models having 4gb memory. So add in the cost of the upgrade to the purchase price of the old model if you want the kind of performance the tests show.