xanzibar,

I solved this problem on my G3 and iMac by configuring the Airport (from the iMac) this way:
(system preferences \ network \ airport \ advanced \ TCP/IP \ (IPv4: = Using DHCP)(IPv6: = automatically). This allows my ISP to send a dynamic server address' back to me (I have been told).

And if you have been inputting DNS address' in "Airport Utility"
delete them and leave the input squares blank.

Since you are on a different machine and OS (if the above does not work) you can try using DNS address' provided via "OpenDNS."