I don't believe Netflix streams at >3Mb/sec very often if at all. The notion that you need 5Mb/sec is not accurate. And while people on cable get speed tests showing their "super high bandwidth", most cable connections probably don't even average 5Mb/sec over a sustained period. DSL on average will stay closer to your "speed test" rating over time, with, obviously, lower rated speed most often.
My DSL gives me ~5Mb/sec -- sustained -- and not only has no problem with Netflix, it seems fully capable of handling OnLive.
There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working.