Wireless Router

I've set up multiple 802.11n routers and tested the range with the Macbook. There is not any meaningful difference between an Airport Extreme/Time Capsule, Netgear, Linksys, DLink &c. It all depends on distance and obstructions between the device and router.

Likely the limiting factor here is the PS3 as it is 802.11b/g so will not get the range benefits of 802.11n.

You can get a secondary 802.11g router that uses an external antennae then replace that antennae with a high gain directional antennae, then disable the DHCP server and connect it to the Airport Extreme, or you could get an 802.11n bridge and plug it into the PS3's Ethernet port. I forget if the Express will act as a wireless bridge.

Edit: Though if the house is too long or the building blocks too much signal wired is the only way to go.

 

As the previous poster mentioned, you could use an Airport Express to extend your network to the PS3. You could place it within a room between your router and PS3 - and it would give the added benefit of being able to stream music to a device within that room.