WDS and bridging are fairly different beasts.

WDS essentially extends a single access point using a second access point at the cost of halving the bandwidth since each access point has to "relay" i.e. receive and then re-transmit the data as you've noticed.

Bridging (which is not what you're calling bridging) makes one of the access points a client to the access point, just like a laptop is a client. It then provides an ethernet output and any wired ethernet can connect to a wireless network. You do not halve the bandwith doing this. DD-WRT running on the WRT54G routers also does some tricks with MAC addresses to make it look like it's all the IP address that live behind it. If your wireless makes it the distance in one hop, this would be the preferred solution in my opinion.

The WDS would however extend your network for all other devices, perhaps out on to the back deck or something.

I'm surprised you are getting 2.1MBps with WDS over a 802.11g network unless you've turned the security off. That's about the most you'd normally see using a single point to point with a reasonable level of security in my experience.