User Security

I need to disable a command button based on the security group of the current user. Is there a property or something I can access that will allow me to do this programmatically? Basically this is what I need to do (pseudocode):

Private Sub Form_Load()
' If user is not a member of the administrator group
' MyButton.Enabled = False
' End If
End Sub

I still want everyone to be able to have access to the startup form, just deny certain functionality to non-admin users. Anyone know of a way to reference Current user permissions? Thanks!