For change the work hours on your outlook calendar I used Tweaks2k2. It was very simple and there's a lot of utilities. The page is
www.pc-counselor.com.
I had the same problem and I posted the same question on
www.todopocketpc.com and Ctitanic (the creator of Tweaks2k2) answered me and safed me.
Sorry about my english I'm spanish, but I hope that i help you.;)