To hide a server from the browser, edit: 

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters 

Add value "Hidden" (REG_DWORD) and set it to "1". 

Reboot the server. It may take up to ½ hour for the server to disappear from the browse lists. 

(Same result can be acheived by executing NET CONFIG SERVER /HIDDEN:YES on the workstation.) 

Key:[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters]
Value Name: Hidden
Data Type: REG_DWORD
Data:(0=disable, 1=enable)