Wireless Network Expansion at Residence

I have a Belkin N wireless router at my home that provides wireless internet . It is using a WEP Code for security. I want to boost the range of it so it can reach to other buildings near the house, garage, and office where other computers are located there to connect wirelessly. I also have a Linksys WRT 300N wireless router NOT being used BUT I could use it to receive the Belkin signal boost it and transmit , put the output of the Linksys into a router switch to be used by multiple computers at the several locations in the buildings described one of which is a server in the office near the house that I would like to also be connected to the same wireless network. How could I achieve the connectivity I am looking for?

I have examined some sites on the NET that describe the use of another wireless router to receive and transmit using DD-WRT Firmware (whatever that is!) it seems complicated or is it?

I can do the work myself but need some guidance as to how to properly connect them or get whatever other devices I may need to do the above.