Check which encryption you are using. If you are using WPA2 for example, does your PC hardware support WPA2 (or even WPA).
Have you downloaded and installed the WPA2 patch for XP as well?
Problems connecting an XP PC to an Airport Base Station
http://tech.ifelix.net/2002.html
If you are using WEP, be aware that WEP is now considered no longer secure and should be avoided in preference to WPA.
One of the problems with WEP is that the actual standard relies on a 10 character HEX key for 40bit WEP and a 26 character HEX key for 128bit WEP.
In order to make things easier for people, vendors use certain algorithms to convert simple alphanumeric passwords (or passphrases) into HEX keys, thus enabling people to use simple memorable WEP password rather than lengthy HEX keys.
The problem is that different vendors use different algorithms to generate the HEX key and therefore a ASCII password on an AEBS will be hashed differently on a Netgear client and vice versa.
One thing is a 13 character 128 bit WEP password will be hashed by all vendors in the same way (if you use 40bit WEP then a 5 character password is required).
Though sometimes not even that works and the HEX key must be used regardless.
Accessing a Airport Network with a Windows XP PC or laptop (with XP SP2)
http://tech.ifelix.net/1011.html
Accessing a Airport Network with a Windows XP PC or laptop (with XP SP1)
http://tech.ifelix.net/1010.html
iFelix
