If you're using Win2K, it's a bit different.
If you go the Display Options, in the Settings tab, you'll see "Multiple Monitors On ATI 9500/Pro" or something of the sort.
Here's my whole problem with ATI's DualView solution in Win2K.
You cannot have different resolutions for each screen. If you set the resolution to 1024x768, the same resolution will be applied to both screens. By default, the Secondary Monitor will be a clone of the Primary.
In order to get DualView working, you need to go to
Display Options -> Settings -> Advanced -> Displays.
You'll have something like this :
In this case, the TV is being used for Secondary Monitor, but let's pretend it's just another CRT or TFT screen.
ATI allows you to :
1. Stretch the Desktop on the right of the Primary Monitor ( Button 5 )
2. Stretch the Desktop below the Primary Monitor ( Button to the right of Button 5 )
Simply click on Button 1 to enable the Secondary Monitor, then Click either Button 5, or the one right next to it, to choose the desktop type.
Hope this helps...
PS. If you click on button 5, your taskbar will be spread on both monitors BTW.