Sharing usb hub?



I just got an iconcepts sharing usb hub that basically allows two computers to share the devices conected to it. I couldn’t find a picture of it but it is this one
It will only be used for devices such as printer, scanner, tablet, mouse etc., not cable modem, drives networking etc.
What I am wondering is could a virus get from one computer to the other through this hub? The reason I ask is that my main computer is not and never will be conected to the internet. It is pretty fast (especially when overclocked) and I really don’t want to go loosing all that nice speed with a bunch of anti-virus/anti-spam/anti-popup/anti-spyware/firewall software. I have another computer conected to the internet that deals with that crap. I very carfully scan files before I transfer them to the unprotected computer, usally via compact flash card (I have several from my cameras and two card readers so it’s a convient way to do it, and I already have the cards).
Both computers are hooked up to the same mouse, keyboard and monitor through a kvm switch, so I can just make a few key strokes and switch between computers. I though this would work well to share devices (primarilly the printer and scanner) between both computers. Is tthier any way a virus could get from one computer to the other if this was hoked up?
On a side note, anyone know of a good way to share speakers between two computers (I geuss I could just get some splitter cables but I’m not sure if that would work)?