Linksys Wrt54g Router - Inconsistent Wireless Signal?

I have a linksys wrt54g wireless router and a few weeks ago my wireless connection started to become inconsistent, it would randomly drop service or be very slow, and now it has become very inconsistent and slow, all the while the wireless signal would be 4-5 bars.On my windows 7 desktop, often times the yellow triangle with the exclamation mark pops up over the signal strength indicator when its at 4-5 bars.I've tried changing to 2 different routers and its the same, and the problem is persistent for all computers in the house.I've connected directly via ethernet to the modem and router and service was fine.There are a few wireless networks in the area,some with quite strong signals, but I downloaded the xirrus wifi inspector and it says I'm not sharing a channel (channel 1) and though I'm ~15ft from the router, the signal is ~65dbm, which seems low and is almost equivalent to neighbor's wireless strength.