[H] wireless access point

[Winterlight]

I have a unused wireless router that I would like to use as an access 
point to extend the range of my current wireless router. I am not 
sure if that would be a bridge or an access point. I understand I 
would first disable DHCP, Unp and the firewall in the old router as 
well as provide it with it's own unique IP number, and then  plug the 
old router into one of the primary router ports.

 So now I have a second wireless router out on the fringe of my 
primary routers range...... but how do I handle encryption? Can it be 
the same as the primary router so the user doesn't have to switch 
from one router  to the other as they move through the house , or is 
that not possible? Thanks

w