Help: Vista and Active Directory 'Browse' issue

I have several Vista workstations on a AD network along with 10's of
workstations running XP and servers running various OS's. The AD network is
connected to a separate much larger AD network (several hundred workstations
and servers). When browsing network places (e.g.: when mapping to a network
drive), the XP machines on the smaller AD network show two distinct
networks, the local AD network and, larger AD network. Both networks can be
'explored' without significant delay.

However, when performing the exact same function on a Vista workstations,
there is no distinction between the two AD networks. In addition, every
time the browse button is hit, the entire list of AD servers and
workstations on both networks is refreshed which can take in excess of 15
minutes before anything shows up, functionally making it impossible to
'brows' the network. This behavior appears to be limited to Vista
workstations. Is there a way to make the Vista workstations respond more
like the XP workstations in this regard? Thanks for any advice.