ramalama: Welcome to the forum. What you need is a transceiver to convert the RF signals from the motion detectors to a power line control (PLC) signal that an X10 switch can use for turning lights on or off.
What is the model number of the motion sensors you purchased? (Just to verify they are not X10 security ones.)
There are a couple options for transceivers, if you want full control of how things work and plan to expand at some time, I suggest going with AHP with all the software plug-ins (usually $50 on the X10 site's deals page.)
For the light switches, there are also options available. If the lights are regular incandescent then you can use pretty much any X10 switch, particularly the ones with dimming capabilities (with most X10 dimmers you do not need a neutral wire available in the switch box). If the lights are CFL or other low voltage lighting, then you will need a X10 non-dimming switch (these type do require a neutral wire).
ramalama Before you jump in and get a transceiver think hard what you may wish to do down the road!
I'd have to agree with Puck get AHP (Active Home Pro) (http://www.x10.com/onsale/index.html) 1/3 way down the page (includes all plug-ins and a slimline remote switch for $49)
* The model number for the sensors is MS16A.
* is a neutral wire the same as a "ground"? If so, I understand the difference.
And yes, if motion-senor control were available for floor lamps I could use a coupla those.
(all of a sudden I have that horrible "newby who knows squat" feeling!)We were all there once! ;) :D ;D
My house is almost 100 years old, and I know that the regular single-pole light switches have just two copper wires attached to them.
From experience (!!!) I know that just one of those two wires carries current. Is the other the "neutral" one?