Right, that's it.. need help..

Those two reported lines that messed up your internet when you changed it, are DNS addresses. They convert a name like abovetopsecret.com to an IP-address (4 numbers) like 75.126.76.151, and that number is used to actually reach the server. So when you changed it, Firefox didn't get the number and couldn't reach the servers to get you the page.

Your ISP should provide you the IP addresses for the DNS servers, and they should match up with those two lines. Alternatively, your modem/router may act as a DNS server, but since those lines contain IP addresses that normally aren't used for internal networks, I doubt that. So the best thing to do is to check any files you got from your ISP for the correct DNS IP-addresses, and then check if this matches up with the TCP/IP configuration of your Windows XP. I believe you can reach it through the configuration panel, but I don't own XP so I'm not sure - chances are though that your ISP has the DNS addresses in the same place as a neat manual how to configure XP to use them.

I haven't checked Mutter's source but I'm pretty sure it uses domain names and needs DNS to work properly. If your DNS really is misconfigured, it might explain those hangups, as nothing will happen till the DNS server responds with the IP-address.

Ehrm,.. Good luck ;] and if anything's unclear, I'll be glad to hear.