[Hampshire] WiFi Channel scanning

I have been having some "adventures" with my WiFi set up recently. It seems
to be getting flakier and flakier.

I'll spare the detailed history for the last week or so, and go straight to
my problems today. I fired up my laptop (in ~doze), but the wireless did not
connect immediately. I went to the wireless network list, hit disconnect and
reconnect. I got a connection for a short while but it dropped out after 10
mins or so. This process has been repeating itself.

The router (Netgear DG834G) has been working fine since I bought it, until
very recently. But for the last few weeks I have been getting quite a few
connection problems, and not on the same clients. Is it known for WiFi to
deteriorate like this? One possibility I considered is interference from the
host of other routers which have invaded in recent months.

So my question is - Is there any software (Doze XP or Linux) which will scan
neighbouring WiFi networks and report back which channels they are using?

Kelvin