100mb is overkill IMHO unless you have a known reason for it. Netflix HD is under 4Mbit. 720p and 1080i are in the 8-15Mbit range if you can find anyone really streaming those. 20-30mbit is probably a good place to start.
Most of the time you should not blame streaming quality on your internet connection, but the content provider or "Internet". Even with 20Mbit, 1/2 the time CBS, NBC won't turn HD in their players. It is them or a bottleneck in the middle not my connection.
Motorola DOCSIS 3! SB6120 is what I am running. Avoid the SB6121.
Router... Linksys continues to have great compatibility with VOIP stuff which is one of my criteria. Trendnet too.
http://faq.nettalk.com/index.php?_m=...barticleid=255