Hi Jamcu,

Download a free program called "InSSIDer" and run it on your laptop.

inSSIDer Wi-Fi Scanner | MetaGeek

That will give you detailed info about what channels your laptop can see in use. It gives you a nice diagram showing where the interference is etc. Your best bet is to align your channel exactly right on top of (not right next to) the least populated hump on the channels list.

Here's an example:
http://images.betanews.com/screenshots/1255701759-1.png
(If that doesn't work just google image search for "inssider".

In that wifi area, the three networks on channel 1 "should" cooperate with each other because they understand each others' traffic. (i.e. they will be aware of each others' sending patterns, but NOT the actual data being sent, and good routers will cooperate.) Notice that the bell-curve shape covers the adjacent channels though. The wifi signals on channels 5 and 6 will NOT be aware of each other, but WILL be interfering with each other. The poor d-link on channel 5 will see everything on all three networks on channel 6 as interference, and likewise will interfere with everything on channel 6.

Channel 14 is there because it is usable in some other countries. Unfortunately that is not in the reserved private band in the U.S. so you can't run any wifi devices that broadcast on that channel here. (If you did, you'd probably have a visit from the FCC.)

In that screenshot I sent, the best channels to pick would be 3, 8 or 9. Unfortunately most areas nowadays look like a giant mess of overlapping bubbles and there's nowhere that gives a reasonable signal except the 5ghz band.

Honestly, my strategy is to just use wires for anything I care about streaming stuff. I have never gotten even halfway reasonable throughput from my wifi in an apartment building. If I copy more than 200 megs it's actually faster to pull over a wire and plug in before copying.

Here's what my wifi atmosphere looks like:



This tells me I should probably move to Channel 4.