Reason why its not able to hold of 7 keys is because USB has a limitations on key pressing, try getting a usb to ps/2 converter, it might solve the problem. (for some usb keyboard yes)
if ur going to buy a keyboard just for o2jam, try to avoid any usb keyboard, mechanical keyboard with black cherry switch will be ur best choice.

This post has been edited by kEazYc: May 18 2010, 08:11 PM