Super TextTwist - description from Softdepia.com:
Features: Play Full Screen (or in a window). NEW! Play "Puzzle" mode without a timer! NEW! Find words with up to 7 letters! (Choose from three modes: 7 letters, 6 letters, or mixed) Thousands more words than web version. Link to online word definitions. Improve your vocabulary as you play. Track your personal high scores. Play while offline. Don't tie up your phone line! (internet connection required to use dictionary links) Download and start playing today! Pay later
Super TextTwist is a "Free to try" program. You can download and try it for an evaluation period.