Dropped Signal Strength on laptop and PS3

i have a linksys WRT54G that is only a few months old. i have one desktop physically wired into the router and a desktop and a laptop connected wireless also a playstation 3 that is also wirelessly connected. i have noticed recently that the wireless connection on my laptop drops from 54 mbps to 1 mbps every couple of minutes or so and i lose all connectivity, then the speed comes back up in a minute or so. i notice this on my playstation 3 as well. the funny thing is that it does not happen on my desktop which has a wireless B card installed on it it constantly stays at 11 mpbs regardless of what is going on with my laptop. My question is, is it the router that is going bad, or could it possibly be my laptop's wirless connection?? i have already upgraded the routers firmware to the newest available. Any help would be greatly appreciated!!
Thanks in advance!

Jon

If 11b and g are off of the same router. You will get a speed pump. Try killing the b and setting up the router for 11g only.