I\'m not offended and it\'s not a silly question, kudos to you for wanting to learn :-)
The Cacko ROM you have is a Qtopia ROM, letting you run your Qtopia apps as you have been doing.
The X11 ROM - pdaXrom is for running X applications, like X applications on a desktop Linux or UNIX system. It\'s a different way of putting graphical apps on the screen than Qtopia uses. You cannot run Qtopia applications on it.
BUT you can run X applications on your Cacko as I do using X/Qt.
http://xqt.sourceforge.jp/This gives you the best of both worlds, if you really need it. I only run Xterm and GIMP. And yes it works like a normal Qtopia app, there is an X icon in the taskbar.
The chances are you don\'t *need* it, but give it a few weeks and who knows... you may find a particular app not available for Qtopia which can only run in X that you do need.
Have fun!