Here it is with WindowState
Code:
Private Sub txtWorksPriceLink_Click()
Dim xlApp As Object
Dim xlBook As Object
Set xlApp = CreateObject("Excel.Application")
Set xlBook = xlApp.Workbooks.Open("Z:\" & Me.txtProjID & "\WorksPrice.xlsx")
xlApp.Visible = True
xlApp.Windowstate = xlMaximized
Set xlApp = Nothing
End Sub