Extending the range of my wireless router with a 2nd one

Greetings everyone,

I have a Linksys WRT54G router that's connected to the internet on the 1st floor and I would like to extend it's range to the 2nd floor. I get a weak signal due to the common obstructions of walls, wood, concrete, etc. I have a second wireless router, NETGEAR MR814v2, and I would like to use this to extend the range of my first wireless router. How would I go about doing it? Is it possible to turn my NETGEAR MR814v2 into an access point? How do I configure it? Do I have to run a cable or can I do it wirelessly? Please let me know. Any advice would be appreciated. Thanks in advance.