I just installed one of these last night, because I was putting my lcd over the fireplace, and the equipment on the opposite wall. I must say it works quite well, and is under $20.00. Works in my opinion as well as the several hundred dollar gefen counterparts do! Check it out.
I heard for HDMI over cat 5 you have to use some special cat 5 for the audio side I believe. Did you use regular cat 5? I almost went this route myself because I had a faily long run of HDMI from my reciever to my projector but ended up using two pieces of HDMI and a adapter and it works surprisingly well. I thought I was going to have to redo it due to noise in the picture but nope.