[操作疑難] Lenovo notebook - Upgrade from Vista to Win 7

我幾年前用學校quota買左Lenovo notebook, 連原裝Window Vista, 想upgrade去Win 7.

請問最平既方法, 係咪買隻upgrade version, instead of OEM / box set?

請問有冇Ching教我去邊度買最抵? 我係咁e行左幾間, 只係見到win 7 OEM / box set... 煩惱中...