Vista x64 Business can not discover XP/2003 machines on th..

Hi,

I have two Vista business machines on my netwrok. One of them can
resolve windows xp/2003 machines names on my local network and other
can not. network settings from all I can see are set up the same using
DHCP. the newer machine can not resolve the names but can see the
other Vista machine. interestingly enough when I view the network
module status both are using my ISP's DNS and do not point to my
router (192.168.1.1). What am I missing? have anybody experienced
anything like this?

Thanks