You may just need a noise filter on the power strip. It may not actually be the powerstrip that is generating the noise, but the TV or something else plugged into the power strip. You should do some troubleshooting to figure out which it is.
Here is a plug-in filter:
[Link: homeautomationnet.com]I don't know if X10 signals will go through it -- you might want to ask Bill of Home Automation Net (who is a participant on this forum).
The coupler/reapeater should not be necessary if everything you are controlling is on the same circuit your controller is plugged in to. You should only need it if you want to controll switches on the alternate phase. If you end up with the IR543 on another circuit,
[Link: homeautomationnet.com]is an inexpensive phase coupler/repeater.
II am not affiliated with Home Automation Net in anyway; I have purchased products from them in the past).
Joe