found this out on another site

"Great info. Just be aware that the 802.11 b/g standard supports only three non-overlapping “center” channels - 1, 6 and 11.

If you have your AP set to anything other than these you will still get interference from it’s closest neighbor channel, ie:

10 - high interference from 11

9 - medium-high interference from 11

8 - medium interference from 6 and 11

etc.

This is because each center channel uses 23MHz of bandwidth (1Mhz guard, 11Mhz below and 11MHz above channel), so the spacing between these is required to allow the most amount of bandwidth for wireless data transmission.

So in short - use 1, 6 or 11 as your channel and you’ll get best performance.

Note: This does not apply to 802.11a or 802.11n (5.4GHz mode) that have a wider range of channels available to them.

Regards,

Shane."

 basically if your base station is transmitting at a certain channel it could be getting interference from a neighbour , like mine , it makes a BIG difference to speed and reliability 

i was on 11 and so was my neighbour , i was getting poor signal and drop outs - changed to 6 and voila !