Let's get this straight. There are:
- DSL modems
- cable modems
- routers without any kind of modem built in, which can work with either
- DSL modems with built-in router
- cable modems with built-in router
Since you already have a cable modem, you just need a plain router. Here's an
example of one. Virtually any router you can buy will have the functionality of a WiFi access point; they used to sell wired only routers, but I think they have stopped that.
What you need to know about WiFi (assuming you even care -- if you are going to use a laptop or can't run cables for your desktops) is that the 802.11n standard is sexy and fast, but not quite done yet. The "draft" devices, such as the router I linked you to, are designed to be compatible with the current working draft of the future standard. They will likely be upgradeable to the final standard with a firmware update, once it is finished. If you think WiFi will be important to you and you will use it for file and printer sharing, buy an "n" device.
If you have no current plans to use WiFi, or you can only see yourself using it for Internet sharing, you can buy an older, cheaper "g" device -- they are plenty fast to keep up with your cable Internet connection. Using wire (ethernet) remains the best option, if it's not going to unreasonably inconvenience you.
