Use this handy little snippet 
VB Code:
Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hWnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long
Private Declare Function GetDesktopWindow Lib "user32" () As Long
Public Sub StartDoc(ByVal DocName As String)
ShellExecute GetDesktopWindow(), "Open", DocName, "", "C:\", 1
End Sub
You would call it as follows :
VB Code:
Private Sub Command1_Click
StartDoc "http://www.vbforums.com"
End Sub