Scan for viruses and spyware. Use a personal firewall on each computer.
Download & install latest firmware for the WRT54G.
Run Windows Update and install SP2 (if running XP).
Download and install latest drivers for your wireless adapters.
If the adapter has newer firmware, update that, too.
What are the model numbers for the wireless adapters?
Do you have any wireless security enabled to keep neighbors off your network?
WRT54G broadcasting in what mode: b only, g only, mixed?
NOTE: Updating the firmware solves many problems for routers.
Yes, my wireless network at home consist of the WRT54G linksys router downstairs in my room, and 2 computers that are wirless clients for that router. One being a laptop and and one being a desktop. The problem seems to be with the desktop computer which is communicating through USB wireless connection from linksys as well. The problem is the one upstairs drops the 48.0Mbps (i get on a regular basis) often, and it drops for a very long time. It goes from 48.0Mbps to 11.0Mbps fast, and stays that way. What I normally do to get the connection back to 48.0Mbps-54Mbps, is disable the connection and re-enable it again. My question is can I put a router upstais to feed off the router downstairs so the computer upstairs has its own router close to the USB wireless connection? I thought the high-gain antennas would work, which they have been, but it seems like lately it hasn't. My next option was to get a range expander to plug into an outlet and try that. Running out of option to expand the range.
2 Story House
Router: WRT54G linksys
High Gain Antennas: Linksys 7dbi
Desktop computer which is upstairs drops the signal often.