Ok, here is something you may try. Since you said you can communicate with your router but not Interent, then it seems that your XP might having problems resolving Internet addresses, and this have probably due to your DNS settings.
Normally, your router will assign you the router's own IP address as your DNS server, which is probably 192.168.1.1 in your case. This should work, but sometimes your computer might don't like this setting. So, you should try putting in the DNS addresses from your ISP. You can get these addresses by login into your Linksys router and then click on "Status".
Then, goto your network card's TCP/IP properties and put those addresses there yourself as your DNS server(s).
If after you've try this, then you can see if it's because of the DNS settings.

Normally, your router will assign you the router's own IP address as your DNS server, which is probably 192.168.1.1 in your case. This should work, but sometimes your computer might don't like this setting. So, you should try putting in the DNS addresses from your ISP. You can get these addresses by login into your Linksys router and then click on "Status".
Then, goto your network card's TCP/IP properties and put those addresses there yourself as your DNS server(s).
If after you've try this, then you can see if it's because of the DNS settings.