[H] Extending a router signal?

[Sam Franc]

I have 2 Linksys broadband routers.
I ran a cable from the main one to the other side oh the house to get a 
better signal on my laptop.
When I power up the second router it kills the signals to my roku and 
other computer.
I have heard of other people doing this.
How do I keep the signals to my Roku and other computer?.
And get  my regular signal out of the second router?
Sam