Adrian Brentnall explained :
So - 'Dear Marge - is this normal ?'
If so - I think I'll just dump the wireless idea and go back to good old
cables!

Over such a very short range, no it is not normal - but wired always
beats wireless for speed and reliability. There are a number of free
pieces of software, which can make use of your wireless card to see
what other wifi systems are running around the same area - not all work
with all wifi adaptors, but one is almost certain to. They will show
what else is around, how strong their signals are and which channels
are in use.

You need to find a clear channel with at least one clear channel either
side of it - make sure your card is configured to use UK channels and
turn your router off whilst it scans. These things are only able to
identify wifi interference from other wifi systems, but there are many
other sources of interference such as microwave ovens etc. able to wipe
the signal out.

FYFI - I have a wifi router which provides a reliable fixed link over
0.5Km in a very built up area using directional antennas. Just so you
know it can be done.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk