Sub test()
Dim DerLig as long, i as long
DerLig = Range("A" & Rows.Count).End(xlUp).Row
For i = 17 To DerLig
If InStr(Cells(i, "A"), "2007") Or InStr(Cells(i, "A"), "2008") And InStr(Cells(i, "A"), "XRXX000") Then Cells(i, "A") = Replace(Cells(i, "A"), "XRXX000", "XRXX100")
Next
End Sub