You said you were using a Hub outside of your wireless router? In other words, your desktop connections come from your router, then to a hub, then to the PC's? If so, is the hub really a hub? Or is it a switch? I have found that when I connected a computer via the second device, I can't see other PC's from that PC, and vice versa. I think Windows 7 gets confused when there is too many network devices between computers.
This is just what I have experienced, try connecting those PC's to your wireless router (assuming you have enough ports to do so) and see if you can view them from your laptop then.