This looks like it's a DNS resolution issue.

At a command prompt, do "ipconfig /all" and look at the output. Verify that
the Vista PC's IP address starts with 192.168.1. If that is correct, verify
that your DNS server is set to the same one as on the XP PCs (probably
192.168.1.1).

If that does not help, when you try to ping the CTRAVEL computer by name,
does it say "Pinging ctravel [207.69.131.10] with 32 bytes of data" or is
there something after "ctravel"? If there is, do the same from an XP
computer and compare the two. If they are different, then you might have a
different primary DNS suffix set on the Vista computer. (It's set in the
same place that the computername is set.)