Just purchased a Targus ACP50US Universal Docking station:

http://www.targus.com/us/product_det...sp?sku=ACP50US

It has built-in video card, sound card, network card and four USB ports (two of them can provide 1000mA for USB devices), a very cool accessary for notebook. Using a USB host cable N810 can recognise the device and so far I got a USB keyboard and a USB thumb drive working. It would be really nice if I can use the Video card and sound card in N810. Is it possible?

It appears possible, though probably not as easy as you'd like or in the way you expect. The display system on the Internet tablets isn't designed for mirroring or extending the built-in display.

That said, the first result to a Google search for "linux targus acp50us" shows that the VGA chipset in your USB dock can work with Linux and even provides information on the small source code modification that's necessary. Compiling the kernel module for your tablet will likely be the stumbling block there.

Lying beyond getting the kernel to recognize the USB-to-VGA chipset is the issue of doing something with it once it's working. aflegg has previously posted a link to an IRC log showing that dragorn on #maemo got an external display to show static images. And to the best of my knowledge, that's the most anyone's done thus far.

Always wondered whether USB2VGA could be made to work with the tablets.

Even static images are good for presentations!