Dual monitors problem

First my hardware configuration Dell Dimension 8400 Win XP Pro. with Media Edition, New Dell 2408 Flat Panel display,orignal Dell E 193FP Flat panel display all VGA & DPI appear good both monitors show the Windows boot-up info the arrow travels from the 24 in. across the 19 in. my problem is using Notepad the Notepad display fills the screen of the attached (19) monitor when I exit Notepad the application stays on the monitor, I have to un-attach the 19 in to remove any thing I drag to the attached monitor, I would like to utilize the dual monitors function I am sure this is an easy fix