Cannot see wireless signal

[#1]

Just got a new/used laptop. Works well via lan, but cannot see my wireless signal to connect to. Other pcs connect to my signal, and I can see other signals and can connect to one very weak, unsecured network.
Atheros network adapter has a troubleshooter, when run this states the "Association Test" failed.
Windows xp.

[#2]

To use a well-worn suggestion, can you uninstall then re-install the driver?
First, though (I assume it is enabled in order to get the trouble-shooter but you never know) are you sure it's enabled (many laptops have a 'switch' or BIOS setting to enable and disable the wireless).

[#3]

Not completely clear, your new/used laptop can see and connect to an unsecured network but cannot even see yours?  If so...
Could your router be running on wireless channel 12 or 13 and your laptop (or specifically the wireless adaptor) thinks it is in the US?  Not all wireless adaptors contemporary with XP can cope with WPA wireless security protocol, but I have always seen that manifest as an inability to connect to a visible network.  Or I suspect an ultra-modern dual band wireless N router might cause problems.   

[#4]

Success :). Changed channel from 13 to 8, wireless signal appeared shortly after.  Hopefully it will stay.  Thanks for the advice and suggestions.

[#5]

Ah yes, forgot that one - there's a lot of wireless adapters out there which only work on the USA approved frequencies (channels 1 to 11), normally simply due to the drivers.
Good call RR.