If you don't do anything about the TV cable and phone line you have just made your TV or PC the surge protection device. Steve is right. It is important to stop as much as you can at the service entrance and be sure everyone is using the same ground electrode system. Then use a strip that incorporates all inputs to each piece of equipment at the point of use. I also like to snap ferrite beads on the signal lines and bond the hell out of stuff.
That may seem like overkill to people who don't have many thunderstorms but it is what we figured out here in SW Florida where a storm is a daily thing for most of the summer.
I had a thousand customers that could not turn off their computers and unplug them every afternoon. We made our lightning calls go from, several a day to virtually zero using these techniques.
