dual monitor problem after OS reinstall on inspiron e1505

Hi - I recently reinstalled windows xp on my laptop, and was unable to reinstall dell media direct or the video driver that came on my dell reinstallation cd. (i accidentally zapped the partitions on my hard drive the first time). i reinstalled again, and was able to install dell media direct, but not the video driver. without the video driver, my laptop and external monitor (e228wfp) didn't recognize each other, so i updated the BIOS and downloaded the avi driver from the dell web site. now the laptop and external monitor are connected, but i can't get my entire display to move from the laptop to the monitor.

any suggestions would be most welcome!