I have a Compaq with WIN2K. When I got it the hard drive was empty. I had a WIN2K upgrade disk and installed WIN2K on that machine via it's own Product Key sticker on the case. So Thursday I bought 18 computers from the US Forest Service. All have WIN2K stickers on their cases with their very own Product Keys. So I stuck the upgrade disk in and used the key provided.... And the error message says: INVALID! So....wha's up wi' dat, please? LOL! Thank you Steve in Lincoln, MT