Update: I did try to add the line

name resolve order = wins lmhosts hosts

as suggested in the 'Samba Slow' thread (though I'm not sure if it is the same problem.)

Also, I have Media Monkey on my XP to play music, and have added the songs on the solaris system to the library. As long as I don't try to browse with ie, I can play those songs regardless without delay, so it does not seem to be a problem with logging in/ out, just with the browsing. Is this a wins problem?