Some background: I live in an extremely wifi-busy area (after 5min of scanning inSSIDer shows ~40-50 APs). The way my apartment is laid out and wired is that wifi signal from/to my WRT54GL (with upgraded antennas) running Tomato firmware can hardly reach from the bedroom to the living room. All the surrounding interference is not making things better.

My current setup is located near the top left corner of the bedroom:
cable modem -> Netgear WNR3500L -> WRT54G(for wifi) -> other devices
WNR3500L must remain running stock firmware and act as a gateway because it's running FCC monitoring module.
I tried using WNR3500L for wifi, but its results were worse than with WRT54G.
I can move WRT54G into the kitchen, which sits in between living and bedroom. However, I'm not sure if Netgear WNR3500L running stock firmware can somehow connect to Tomato to extend its range. Unfortunately, I can't run Ethernet cables into the kitchen. To better understand my apartment layout, here's its layout: