Before WinXP "improved" networking, you could control whether a computer participated in Master Browser elections via a Property in the File and Printer Sharing for Microsoft Networks service (Figure 9).
Figure 9: Controlling Browse Master election - Win98SE
You can still do this in WinXP, but the control has been moved to the Services Management Console (Start > Programs > Administrative Tools > Services) shown in Figure 10.
Figure 10: Browse service in WinXP
To stop a computer's participation in the Master Browser election process, just double click on the Computer Browser service and set it as shown in Figure 11. This doesn't prevent the computer from obtaining the network list from whichever computer becomes the Master Browser, but just keeps a computer from becoming the Master Browser.
Figure 11: Browse service disabled
If Registry hacks are more your thing, Start regedit and navigate to (Figure 12):
Figure 12: Browse service Registry key
Change the MaintainServerList key to No, save the key, close regedit and reboot.
No matter which method you use, select one computer that's always or most frequently on that doesn't have a wireless network connection and let it run the Browse Master service.
TIP: When you disable the Computer Browser service on each machine, keep it shut off until only the Browse Master computer is left. Then turn on the other computers, one by one.