Yup...if it's all based on KNOWN tourny winnings, then there's no reason to doubt the list...however, the list doesn't really mean much since the winner of EACH SUCCESSIVE WSOP will take over #1!!!!!!!
It's going to be a few more years before we really have a good system of measurement...a post "boom" (ie...Moneymaker) tournament wins = points ranking which people are starting to put together. Something VERY much like the world rankings in tennis and golf where you have to be in certain tournies to get points (minimum buy-in/format, etc) and that the most recent 12months count the most sorta thing.