1. Cable is going (eventually) to a new protocol called DOCSIS 3.0 (much faster speed).
2. The Internet is changing to IPv6. Get a modem that supports both.
I just purchased a Cisco DCP3000 that supports the new DOCSIS and IPv6, and is Gigabit output. For a router I have the D-link DIR-655 Gigabit wired/wireless N.
These two together will serve you well into the future. And I hate to brag, but here is a screenshot of my Roadrunner cable speed after I installed the modem.
I recently changed to Charter from ATT DSL. The modem that they provided (rental) is Motorola Surfboard SB5101N. Is this modem the best option if I decide to buy rather than rent? Also what router should I need to optimize the service? No gaming or other uses, just internet connection for laptop, iPad & iPhone.