If you're a heavy Internet user like myself, be sure you test the modem for quality and reliability. My very first cablemodem was a Linksys v1.0 and it handled my usage pretty well. I had no disconnect issues and everything was grand. When they released the 2.0 version, I could never use it to the max capacity without it resetting on me. The cable light would just go black and I'd have to unplug/plug the unit to get it to work again. Very very frustrating! The Motorola SB5100 also could not handle the Internet usage and would just kind of lock up and surfing was shaky then. The modem I have now is a Toshiba PCX2600 and I absolutely love the thing to death! It never disconnects no matter how much traffic I create. I have ran as many as 12 BitTorrents without issues. Running only one BT before would crash both of the SB5100 and v2 Linksys.
I was talking to a friend of mine and he did some analyzing and he came up with the conclusion that the modems couldn't handle so many open connections as the Toshiba and Linksys v1. He was thinking the routing table got full or the processors inside just simply couldn't handle the traffic. When we run LAN parties (70-150 people), we use my modem!
Cliff Notes: make sure your modem can handle the Internet traffic you make!