Thanks for the help, guys. Earlier today I downloaded the latest Nvidia detonator drivers, and they successfully activated the TwinView feature in Windows 2000 for me. I see what you mean about that annoying feature of horizontal span. Do you notice that this does NOT happen when TwinView is activated in Windows 98?
In Windows 98 the screen resolution stays at 1024 x 768 for each monitor seperately, meaning that when a window is maximized it only covers ONE of the two monitors. In Windows 2000, however, the resolution automatically sets at 2048 x 768, and there doesn't seem to be a way to manually overide that without disabling the second monitor. This means that when a window is maximized, it covers BOTH monitors, and this is very frustrating. The only partial workaround that I've found is to resize the windows by clicking and dragging, rather than by maximizing. This takes time.
One final thing: when I downloaded and installed the latest Nvidia detonator drivers for Windows 98 (I have both OS installed and can switch at startup), they DISABLED TwinView in Windows 98! I was forced to reinstall the Asus drivers that came with the card. Thus, ironically, the situation for me is that in order to have TwinView in Windows 98,I must NOT have the detonator drivers installed, while to have TwinView in Windows 2000, I MUST have them installed. Wierd, eh?
Oh well, guess I can't complain. I finally have TwinView activated at least to a certain extent in Windows 2000, which is what I was aiming for.