RE:System Serial Number Please
En la registry: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion
el valor ProductID, con las API's de la registry lo obtenes:
Public Declare Function RegOpenKey Lib "advapi32.dll" Alias "RegOpenKeyA" (ByVal hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Public Declare Function RegQueryInfoKey Lib "advapi32.dll" Alias "RegQueryInfoKeyA" (ByVal hKey As Long, ByVal lpClass As String, lpcbClass As Long, ByVal lpReserved As Long, lpcSubKeys As Long, lpcbMaxSubKeyLen As Long, lpcbMaxClassLen As Long, lpcValues As Long, lpcbMaxValueNameLen As Long, lpcbMaxValueLen As Long, lpcbSecurityDescriptor As Long, lpftLastWriteTime As FILETIME) As Long
Public Declare Function RegQueryValueEx Lib "advapi32.dll" Alias "RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal lpReserved As Long, lpType As Long, lpData As Any, lpcbData As Long) As Long