is a tech coming in to your home to set it up or are trying a self installation?
if your not going to be watching tv then you dont need a splitter, just run the line directly into the modem.
well i prefer seperates meaning one device being the modem, and one device being the router/wireless router.
i prefer renting the modem, simply because i can always return it and get the next best one out on the market without have to paying anything extra except for the monthly fee. also if it ever breaks, then i can get a new free of charge. if you buy your own then if it breaks, you have to deal with the manufacturer to get it replaced, and if its out of the warranty period then you will have to either purchase another one which cost about $70-80 or start renting the modem from them.
i like the motorola Surfboard SB5100 series
you can pick up a wireless router for about $40-50 from newegg.com i prefer Linksys routers.
if you dont need wireless then just get a regular router for about the same price again i prefer linksys products.
wireless
http://www.newegg.com/Product/Produc...82E16833124010
wired
http://www.newegg.com/Product/Produc...82E16833124007
if you can get the coaxial cable line close to your computer then do it and just run a cat 5 cable to your computer, its a lot easier and less of a headache then having to deal with wireless, and all the configuring that goes along with it, especially if you dont know how.