They are giving you the worst case scenario
Most likely, your cable will be ok
Is he getting the Dual tuner HDPVR?
If so, then he will need another cable to the tv location
I would recommend getting the 9242, so he can record and watch 2 separate programs
The 6142 will be able to record too, once the USB is activated, all you will need to do is add the hard drive......
To see if you need a new dish, go and look at it, and see if the LNB (Tip facing into the dish) is attached to a y bracket, with a space for a 2nd LNB (this is needed to get HD signal)
If it has the space, then the tech will install the 2nd lnb, and necessary switches for you free of charge, or upgrade you to the new dish if you have the old one