as i said, if the tablet manufacturer allows to share the wifi via usb, ok, will work
as usafret says, doubtful
even if you manage to make it work, the tablet will start to overheat because it can't enter sleep mode or you loose connection and the usb port will not keep it well charged, this is a half solution if it manages to work in some way
if it works, expect the slowest connection, lots of lag if you try to play with it, connection via wifi then usb to desktop, that is a enormous bottleneck in many levels
easier to buy a wifi card for the desktop, being usb or pci express, what pc do you have? what is your budget?
distance from the pc to the new wifi only router? what wifi router you got?