1. the focus of that site is silent PCs. From that standpoint a 3.2 GHz P4 is high power draw thus a "high" P4. They don't chase the top end they find the sweet spot and go for lower power/noise.
2. The 3 examples are actual hardware they had laying around to test. They didn't mean for them to be an apples to apples comparison so it can't be "cheating". Notice that each of the 3 used a different brand and model of power supply. They could have easily used the Seasonic PS for all three systems and lowered the power usage slightly for the other two. Every power supply they used is more power effecient than anything Dell would ever use.
it's just another site with data, admittedly it isn't the data that investors most strive to see but it is scientifically valid and thorough so it is a valuable base when comparing to "review" sites that have other agendas/criteria.