Try xwords, which is freeware. I believe it's much stronger than the handmark version, you can use your own dictionaries, it's very fast, has game history, etc.
Right now it just picks the highest point word, without regard to rack leave, but it's still very tough to beat.
Also, the author is currently working out some bugs that have been causing occasional lockups on some units with WM2003.
It's a great game.
http://xwords.sourceforge.net/
Mark