ATT DSL - Getting Constant Signal Drops?

I currently live in a fairly-large apartment in Downtown San Francisco and as you can probably imagine, I have ALOT of interference with nearby residential and business wifi's, microwave's, cell-phones and all that jazz.

I currently have the ATT Elite DSL package, which is I believe the 6MBPS(?) package? Anyway, it's the $40 package and I want to say it's either the second or third up from the basic 19.95/month subscription. Here's my problem: ever since I moved into this building, I get signal drops on my ATT all the time--like at least once an hour if not more often. I had a technician check the wiring and he even replaced the router box (they always do) in hopes of improving the situation but so far, no dice.

I have tried switching to different channels after using scanning to see what channels other internet users nearby were using, but I did not see any improvement.The best solution I've been able to come up with is to set my router to be on 802.11B only. For the most part,I have not disconnected but I do feel a certain amount of slow-down or lag compared to my 802.11G settings.Now,I might be paranoid but it certainly does take a good amount of time longer to load up pages and such as compared to previously.The tech suggested I look towards getting an 802.11A/N router, but alas ATT does not support routers of that caliber...not sure why. It's been years and they're still stuck with the 2Wire 2701HG-B model for DSL.