Getting DirectX version

I am creating a game that requires DirectX 7, how can I get the DirectX version(if lower than 7, DX setup will start)?

Code:

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Function IsDX7 as Boolean

  On Error Goto NoDX7
  Dim DirectX As New DirectX7

  IsDX7=TRUE
  Exit Function
NoDX7:
  IsDX7=FALSE
End Function

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That should do it.