Could you expand on this? What have you done to install the driver so far, and what are the symptoms telling you that the installation failed?
It's no longer a problem now. I used the Duemilanove usually, what I yesterday do is to find the driver path(arduino-1.0.1\drivers),and install it just like I do with FTDI chips.
My computer system is WIN7,and what I need to do is just to power off the UNO,and replug to the computer. and it will install the driver itself, then the USB device will turn to a serial com(such as COM7).
The reason I do this experiment is because I see that UNO has some function such as keypad,mouse,MIDI device which the Duemilanove does not have.
Are there some projects or tutorials to teach us to do with these added functions?