The White House truly must think enough Americans are stupid enough to believe the hype about "activist judges". The way that Dubya talks about the subject, you'd think there was a small cadre of judges who were willing to subvert the Will Of The People (TM) in order to push an agenda which is far removed from The People's best interests.
Dubya didn't pass his civics classes in junior high, I guess. Either that, or he's using the term "activist judge" as a cynical ploy. Take your pick.
All judges are "activist judges". After all, the Judiciary is part of the government, and their role is not at all passive. There is much more to their job than to try the accused or oversee lawsuits. Indeed, a major part of their job is to not only interpret the law, but to determine whether or not one law is in conflict with the Constitution, either on a state or federal level. As constitutions are universally considered the highest law of a jurisdiction, if a law conflicts with the constitution in question, the law is considered invalid. It's a pain in the ass, especially if you'd love to issue edict after edict... er, I mean law after law.
Any student of American history should be able to cite a few cases where a judicial ruling resulted in vast social change. Uusually, in the end, the change has been accepted as a good thing, regardless of whether the change was in accord or disagreement with the ruling. Therefore, do not be scared off by the notion of activist judges--they're the best kind.