question about Duemilanove board

Hello, I am wondering to buy this board but first I want to know if it could be used as well as XDIMAX "sub20" board. I mean USB to GPIO converter. This board is using libusb library and its GPIO can be accessed using its library. If it is possible to do such thing with Duemilanove? If yes, then will I have to install only ftdi driver and use some library to interact with GPIO pins? Where is that library? Please help.

Thanks.

"Firmata" does something similar to this. http://firmata.org/

It doesn't sound quite the same as the sub-20, but it should provide some of the same capabilities...