802.11b bandwidth fluctuation?

Hi all...

Am having a problem with my 802.11b connection. At regular, periodic
intervals (probably 60-120 seconds, though I haven't timed it
precisely), the throughput I get drops down to nearly zero, then climbs
back up, then down, ad infinitum - if I use a bandwidth graphing tool
(such as the statistics tab in Azureus) the result looks more or less
like a sawtooth graph.

I live in an apartment building, and I know that there are at least two
or three other access points nearby - not sure if they are 802.11b, g,
or something else. Might there be some sort of interference from these
that are causing this issue?

I know its not my DSL connection itself, as if I plug my computer
directly into the router via 10 Base T, the problem dissapears, so I
think it must be some sort of interference, but I'm not sure.

If any one has any suggestions as to what I might try in order to
alleviate this problem, I'd be very grateful to hear from you.

Thanks in advance.