Hey psychoticape, I hope you dont plan to take anything that the makers of UT made. Even if you made the game, & gave it away for free, you can still be nailed leagaly for it.
If I were you, I would just go get Worldcraft Hammer edition, or buy Cartography Shop & make your own. I find that worlds are easier to make than code is, so it shouldnt be too hard.
The law states that if you make a game, using copyrighted material, you can only make one copy of the game, for personal use. If you plan to distribute your game, you will need to use your own content, or get the makers of UT to allow you to use their levels.