Thank you for your replies. They helped me get a better handle on things. Comcast does not "give" anything away. They will rent me a DOCSIS 3 cable modem for $7 a month. The last modem I bought was $40 and I've had it for more than 60 months. I can buy a new "approved" DOCSIS3 myself for $72 and avoid the monthly rental fee. I understand an analogy would be I am on a WindowsXP system where the new modem is like being on a Windows7 system. My concern is what does the $72 really get me? I currently can stream Netflix to different devices (Roku and DVD player) with out a problem. Supposedly my maximum Comcast contract download speed is 6 Mbps although in practice Comcast says I may expect about 80% of that or 4.8 Mbps. According to a SpeedTest.net check a few minutes ago, my download speed was 4.95 Mbps although at other times it can be around 3.06 Mbps. Maybe everyone is in the shower then and doing laundry ;-) A good analogy though.
If the speed coming in to the modem is 4.8 and my current wireless router is providing rates of 24-48 Mbps (topping at 54) and my computer(s) can handle up to 100 Mbps (or higher), I may be seeing a marginal increase in download speeds, but I am not clear on what that increase would actually convert to. YouTube videos will not play faster although some usually unattended software downloads might be slightly quicker. Is that worth $72. Am I doing anything wrong in my thinking or overlooking something obvious? Thanks again.
Update 9/12: I need to remember, never ever listen to a 'Comcast service tech.' They are the ones that first said I needed to get a new modem to improve my speed. On the Comcast site itself, it only recommends the DOCSIS3 cable modem system for high powered users-those paying for 50 Mbps and more download speeds. I just ran some more speed tests and got over 6 Mbps down. Hence whatever is going on it would seem my 'ancient' cable modem can still handle all the speed that I pay for.
Interesting speeds though-like who do you trust?
speedtest.verizon.net reports I have 1.52 Mbps down and 1.52 Mbps up
speedtest.comcast.net reports I have 6.45 Mbps down and 3.27 Mbps up
reports 6.13 down and 3.13 down
I think I will wait until my modem breaks..