How can I speed up finding/listing other machines on my network?

When I open up an Explorer window to look at other machines on my network, for the first 30 seconds or so, the only thing listed in the window is the machine I'm physically using. The address/progress bar shows that the machine is indeed doing something, but I can't figure out what it's doing during this time, or why whatever it is doing takes so long. Older machines running XP have no problem figuring out which other machines are on the network in a fraction of a second, so what unnecessary work is this one trying to do that's slowing down the enumeration? My current workaround for this is to open a Network window when starting up the machine even if I have no immediate need for it just to have the list available if & when I do need it, but that's pretty lame way to deal with this slowdown. Anyone know what I can do to speed this up?