Recommended setup for my network

I have recently added to my network and would like some advice for the best performance setup.

I live in a two story home and equipment is spread throughout the house.
internet connection is roadrunner business class.

Main router is Linksys WRT600N
Linksys wrt54gs with DD-wrt setup as bridge
linksys voip adapter
xbox 360
Nintendo Wii
Dell Demension Desktop
Dell XPS laptop
Acer Laptop

Wrt600n is upstairs in spair bedroom with modem.
wrt54gs is downstairs with linksys voip adapter connected to it
Desktop is downstairs with pci wireless network card installed.
Xbox is upstairs opposite side of house of wrt600n.
Wii is downstairs opposite side of house of wrt54gs bridge.

would i benefit to have desktop hard wired to wrt54gs bridge or keep wireless card in use?

How would I get the best signal for all pieces of equipment?