Router as signal replicator?

I live above my friend's grandparent's law office and my friend and I share the internet with theirs downstairs in the office.  Thesignal is crappy in half of our apartment and cuts out frequently.  (We have very thick plaster/sheetrock walls)  The router/gateway downstairs is a standard 2Wire provided by ATT.  I have a spare Linksys 300n router with the latest version of DD-WRT installed on it.  Can I use this router as a signal replicator?  Can I just have it rebroadcast the signal from downstairs into our apartment?

I think I found my answer here. http://www.dd-wrt.com/wiki/index.php/WDS_Linked_router_network  I'll tinker with it later tonight and see if I can get it up and running.