There are two good D&D movies out, by the way, though they go the direction of spoof comedy; namely, "The Gamers" and "The Gamers: Dorkness Rising", both by Dead Gentlemen Productions.
Several animes also portray the fantasy milieu well, and the rumor is that the original "Record of Lodoss War" was based on the creator's own home D&D campaign.
Honestly, though, I don't believe it is possible to make an honest-to-goodness "Dungeons & Dragons: The Movie". The game is much too open-ended for there to be a coherent, resolved-in-ninety-minutes story to be told. Many of the greatest stories D&D gamers have are not of epic story arcs, but rather of individual battles or other high points. I could tell you dozens of stories of my various characters' hijinks, like the time my wizard telefragged a piscoloth, and many of them would make a great short, but none would make a good feature film.
There are certainly D&D novels which could be adapted to a movie, but then it isn't a D&D movie, but rather a Driz'zt movie, or an Elminster movie, or Mordenkainen's Movie Madness.