Wireless setup question

Before I spend money on new hardware I want to run this question by somebody to make sure what I am planning will work.  I have an existing home wi-fi setup using an Actiontec DSL router/modem with built in wireless.  But I have large home and the coverage is not good.  What I want to do it use an existing cat-5 line that runs from where the router is to the other end of the house, where I will connect it to a new 802.11n wireless access point.  I am already using existing cat-5 cables in the house to create wired connections for a couple machines so I know the cable should be good.  Does this sound do-able?  I am correct that I need to buy an "access point" *not* a router to do this?  Will I have to turn off the wireless on the original router or can they both co-exist?  Any other advice/suggestions?