I use Xantech stuff to distribute my IR. It includes something similar to the Buffalo module referenced above.
I started with a Xantech
291-KIT Hidden Link Kit. It includes an IR receiver (that would go in each room), a module like the Buffalo one, a power supply, and mouse IR emitters. The receiver in the "remote" rooms is a 1"x2"x3" box. It's pretty unobtrusive and could sit anywhere. There are other receivers as well that are easier to hide.
The 789-44 Connecting Block (like the Buffalo one) sits near the equipment you want to control. You need to run 3 wires (out of your cat5) between the block and the receiver (power, ground, signal). You plug IR emitters into the block and connect them to your equipment. You could also use a single blaster but I use individual emitters.
You can connect more than one receiver to the same system. Just run all the wires back to the block. You may be limited by run length and available power from the power supply but I doubt you'll have problems with the system you described.
In my system, I have 2 receivers, a connecting block, and another smaller block - all wired into a single zone, but controlling equipment in two different rooms. I have the wiring for 3 zones, but I haven't gotten around to using it yet (1 pair of cat5 for power/ground, the other 3 pairs are zone-x/ground (x=1,2,3)).
One of the receivers is next my PC running HomeSeer and with a connected USB-UIRT. You can build a direct link between the USB-UIRT and IR wiring, but I use a receiver anyway. I do this so that I can use hand-held remotes in that room. If I only had the direct connection and no receiver, I couldn't do that. I have an emitter plugged into the back of the USB-UIRT and stuck to the front of the receiver. This allows both automated and manual control through that receiver.
The USB-UIRT can control up to 3 zones. I will feed those into my 3 wired zones when I get around to it.
This description is based on the Xantech stuff that I use. Working with Buffalo or anything else should be similar. I believe that the Buffalo and Xantech stuff are compatible with each other but I'm not sure about others.
I don't think Buffalo has a receiver similar to the Xantech
Hidden Link IR Receiver. They do have one that's made to mount in a wall or cabinet, though, which would be less obtrusive.
If you decide to go with Xantech, make sure you shop around. The variation in prices is extreme. Also, you can wire some of this stuff pretty easily yourself if you want to. Some of the connecting blocks that are sold are really nothing more than some jacks and wiring - and maybe a few resistors (it depends on the function of the block). I went with mostly commercial stuff when what I needed was available and not too expensive because I felt the time saved could be used on other projects.
I bought most of my stuff from
Worthington Distribution. This was before some other places were around (like Automated Outlet).