charter does not have wireless modem/router combos in the fashion it sounds like you want it for. you would have to subscribe to the home networking service (as the prior 2 posters have eluded to). You cant just rent the wireless modem. The router lease is about $5 a month, it costs $99 to install it i think.
in most areas that have HN, i think you can buy the 'wireless gateway' (router) for $150 instead of leasing it. sometimes you can do the install yourself but usually not.
my opinion? go to your local computer store and buy a wireless router. it would be less expensive ($40-$80 for the router and $40-$80 for the wireless adaptor) and they are not that difficult to setup. Just dont step ahead of yourself in the configuration - read the manual and you will be fine. -- Yes. the cat in my avatar is indeed mine.
With wireless routers so cheap these days. I would think you can get one yourself and save a load of cash not paying charter each month for the equiment. Mine set me back a whole 20 bucks. and that was a G router