You are correct that this is the most popular measure among economists. If I don't miss my guess, you are using the CIA World Factbook numbers for GDP per capita, which are converted via a PPP rate rather than an actual exchange rate. I happen to prefer real exchange rates (which puts the U.K. at $35,736 for 2005 (from here and the current Bloomberg rate of $1.77 per pound), and China at considerably less than $6,000).
For what it is worth, another implication of using PPP rates for GDP would mean that with China's new-found GDP statistics that it is already growing close to the U.S. GDP when adjusted for such PPP.