You can use the ShellExecute API
VB Code:
'put this in a module or decalre it as private instead of public
'declares for shell by association
Public 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 Const SW_SHOW As Integer = 5
Public Const SW_NORMAL = 1
'then whereever you want to open the file do this
dim ret as integer
ret = ShellExecute(0&, "open", File1.Path & "\" & File1.FileName,vbNullString, vbNullString, SW_NORMAL)
If ret < 32 Then
msgbox "An error occurred"
Else
msgbox "it worked"
End If