Macbook and spotty wireless-n problem (on two routers)

OK, this is driving me totally crazy, and I don't know where to turn.

I bought my MacBook in June, with a Linksys-N router. From day one it was funky, not getting a very strong signal. But after multiple calls to tech support, I tweaked it to the point of working perfectly.

Then, about a month ago, the problems started again (I think after I turned off my cable modem and restarted it). Every so often, sometimes minutes, sometimes hours, the connection drops to three out of four bars (no matter how close I am to the router or where I position it in my house). Then, Web sites don't connect. I hit reload about five times, or open up iStumbler or Internet Connect, and that usually kickstarts it into action.

Finally, I returned the Linksys router and replaced it with a Netgear WRN384 router. Same exact problem. I took it to the "Genius Bar," where they replaced the Airport card and "re-seated the antennas," whatever that means. Same exact problem.

I have no idea what to do. I'm thinking it is some interference in my house, but for years I had a Linksys Wireless-B router with my old iBook. Never ever a problem.

I'm trying to think what's changed since June, and the only think I can think of is the addition of two compact fluorescent bulbs in my living room. But I turned those off and plugged in the router on the second floor, where there are no CFC bulbs. The problem reared its ugly head again.

I have no clue what to do. The problem does not occur at my office, where we have Wireless-G, or at the Apple Store (of course). According to iStumbler, I'm the only person on my channel (tried 1 and 3).

Please, please, please help!