I have run into this very issue previously and can tell you that the newer consumer (linksys, belkin, etc?.) implementations of WDS (wireless bridging) are not worth the time.
1. You will lose half you wireless bandwidth when bridging. 54g gets maybe 20mbps, when bridged that will get cut to 10mbps, I was getting about 7-8mbps with the bridging overhead. It worked ok for gaming from the upstairs LAN.
1a. The don't support there high speed modes when bridging also, so no 108mbps or 125 HSM.
2. The newer routers/AP?s do not support WPA security while in WDS mode. That leaves you with WEP. This was the deal breaker for me. And is not listed up front on a lot of the documentation, get the manuals online and look for how to set up WPA and bridging.
I had 2 belkin (F5D7231-4) 54g wireless router running in WDS mode, and It worked fine until I saturated (7-8mps) the link when uploading large amounts of data. It would cause one of the routers to hard lock and need to be reset to factory settings to get it up and running again.
Unless you going with business class bridging like cisco gear, I would recommend against it.
The current set up I?m using now is a Buffalo WLI-TX4-G54HP Ethernet converter and a Buffalo WHR-HP-G54 router (only using it as an access point) with WPA tkip security set up. My internet connection is Verizon FIOS, and I can pull all15mbps download from the second wired network using the Ethernet converter which is basically a wireless client with a 4 port switch built in. The both support 125HSM so they should get good throughput when bursting. And I?ve already sent a 30GB backup over the link saturating it, and didn?t have any issues.
The buffalo?s also support replacement antennas so you can get some higher gain ones if you run into issues. My two wired networks are about 100ft from each other on opposite sides of the house on separate floors. The client Ethernet converter lists the network strength still at 100% or 99%, the radios in the buffalo equipment are pretty good.
I have not tried the openwrt 3rd party firmware on any of these, their wds implementation is suppose to be superior to the manufactures if your hardware is compatible the openwrt firmware. They may even support WDS and WPA at the same time.