GA, I've used both the RF wireless switch to control a hard-wired receiver to turn on a light (saved me from running a switchleg thru an impossible room to fish) and I've used the x-10 transmitters and receivers with success. I will caution you that the x-10s don't "play well with others" when fluorescent lights are in the same vicinity.
My experience with X10's is pretty much along the lines as HLCbuild states. More modules than I would like have also proved to be extremely short-lived. The principal benefit in my mind (other than simplicity of installation and use) is that they are relatively inexpensive.
