Current home coax...

My home was built in 1986 and had coax ran to each room at time of construction, but what kind of cable was run, I do not know. I am currently using local cable company for TV, Internet, and Phone service. The cable company ran fiber optic to my home about 7 yrs ago up to the cable box on the side of house. With my current cable HD DVR, I am supposedly getting HD broadcast. I do notice a difference in volume and picture quality when I go from one channel to the same channel that is broadcast in HD...(lots of duplicate channels that cable company brags about in the number of channels they offer). DIRECTV is scheduled to be installed this Friday, 11-4-11, but the sales rep. said that considering age of my home, the installer may have to run all new cable to each room, at an additional cost....How can I be sure I have the proper cable? I have looked at some of the current wire and can not see any numbers or markings on it.