Given that you have a router, you really don't want a 2nd one. It would be better to have a wireless access point (WAP) instead of a wireless router.
With a WAP, you'll connect it to your current router, and there won't be too much else to do (except fiddle around with security settings).
If you want to use two routers, you'll need to disable dhcp on one of them. In general, just kill the router features so it acts like a switch.