Check out Ubiquity Gear.
Ubiquity runs a large number of the networks behind the folks @ www.Wispa.org
We use their gear as well for backup microwave links for the datacenter when all the fiber into the facility fails.
We move well over 100mbps over the links AND they can handle Numerous connections - in fact we push an entire /20 over them
A good unit that could support 40 clients easily is the Air Router from Ubiquity http://ubnt.com/airrouter
There are other options - but either one of these would work great.
We are not affiliated with Ubiquity in any way... just love their gear.