Like Lays Potato Chips, I bet you can't have just one.
You will need an
1. IR543 (takes the Ir signal from your Sony Remote and translates it to X10, then sends the signal via your powerlines to the lamp module)
2. A Lamp Module (various part numbers.)LM471?
3. A way to teach your Sony the X10 Codes.
You could get the above equipment from several online sources.
www.homeautomationnet.com is one.
They have a universal remote that has X10 codes built in.
Since you will not want to stop at one lamp, go ahead and get one of the starter kits, it will have several of the pieces you will need anyway.
PS If you need to control a light fixture rather than a lamp, you will need a wall switch instead of the Lamp Module.
Check out the the site I listed, and read through the threads here.