The way the URCs work is that the remotes can emit either IR or RF (or both) and this is set up in the PC software that comes with the remote. Very few components can actually receive RF as an input, so the RF is just a way to get signals from your distant remote to the RF-receiver box that sits near your equipment.
Once the RF signal is picked up by the RF-extender box, it translates the received RF signal into IR and sends it out either via a front "IR Blaster" that is a part of the extender box (i.e. to hit all of the equipment in your closet at once with whatever signal is received), or it sends the signals to one of six IR emitters that are attached to the RF-box and can be run to distant locations (i.e. a projector) to pipe the signal there as well. This keeps you from having to point the remote at the ceiling to hit the projector's IR input as the directly run IR emitter goes right to the projector's input and is attached via adhesive right over the sensor so that it gets the right signal no matter where you point the remote.
Aside from using for a projector, a lot of people use RF-capable remotes to operate equipment that sits inside an entertainment center that does not have transparent doors so that you don't have to have the cabinet doors open to run your equipment.
It's nifty stuff.
Jason
