Thanks for the replies, guys.

Using an alternate port for the laptop with UPnP definitely works, but what I found to be the best is to select "Do Nothing" in the Advanced -> Firewall Config on the laptop. It realizes it's behind a firewall, but then goes into Turbo-Charged Leaf mode and actually downloads faster than the Ultrapeer tower.

Go figure.

And yes, the tower does have a static IP, which helps for lots of inbound connections, not just P2P.