DigitalWitch,
I had the same problem, I added the plug-in, activated it, went to use it by going to the settings option of WP 2.5 and there was nothing there to manage the ordering of pages. This is what I did to get it working(since there were multiple things done, I can’t tell you which one resolved the problem): I went back in to plug-ins, deactivated the page_order plugin, logged out of my site, logged back in, reactivated the page_order plug-in, navigated to the Manage section of WP and there as one of my choices was the MyPageOrder item. Remember this plug-in, like TrishaM said, is in the Manage section vs. the Settings section. I hope you already fixed it or that the additional information will help you fix it. The ability to manage page order should be built in to WP (in my humble opinion) but in the mean time this plug-in works great!
-bobg
