When installing an OSX Server at client locations that required serving to PC's as well as Macs, I ran into problems with PC's winning the browser election instead of the server. Now traditional SAMBA expertise would say that setting the OS level high (like 65 or so) would cause the machine to win the election. But this is no longer true with Win2000 and XP. A Win2000 machine will trump Samba or Win98 regardless of OS level. An XP machine will trump everything else too.
So to solve this you need to edit the registry on the PC's. Here is how I solved it.
On the PCs, go to the "run" command and type in "regedit", then go to HKEY_LOCAL_MACHINE -> SYSTEM -> CurrentControlSet -> Services -> Browser -> Parameters. There are a couple of settings to look at. The results of these settings can be weird sometimes, so you may have to experiment. The two items to look at are IsDomainMaster and MaintainServerList. Microsoft has a good article on it. The basic settings are:
IsDomainMaster = TRUE or FALSE MaintainServerList = No, Yes, AutoBy default, the workstation should say:
IsDomainMaster = FALSE MaintainServerList = AUTOHowever, I've seen it other things, and I've seen workstations override domain controllers in the elections. For the machines you want to be master (for your OSX server to win the election, NONE of them can be master), set them to TRUE and YES. For the others, leave them at FALSE and AUTO.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030224081842949