If you are not to technically savvy I recommend D-Link wireless routers. In my area they are normally cheaper and easier to setup. Otherwise myself I like to use Linksys products.
As for security one you hook the wireless router to the cable modem things are secured through the wire. What that means is that your wireless is still WIDE OPEN. You will want to log into the new router/wireless router and change your log on information and setup the type of security you want. WPA is a very commonly used security option, easy to setup, and provides more security than WEP.
I hope this was of some help or at least gets you into the right direction.