Also, to answer maakya's question about not connecting with wire, this is what I did:
I had an old linksys router. I changed that into a repeater by following some instructions online (don't remember where.. you can google it).
So the linksys router was picking up the wifi from my dlink 825 and then repeating the signal. However, with a repeater, the speed drops significantly.
I didn't need to change anything about the dlink router which was connected to the modem.