If the COA is no longer on the case and you are sure that you have a genuine MS install CD you can ring MS for a new Product Key but you'll need to read the numbers off the inner ring of the Original CD and they will then E-Mail you a new product key in 7 - 10 working days. Now if you have a company built box like Dell, HP, Gateway or something else you'll need to ring the makers of the box and give them a model & serial number again this is on a sticker on the outside of the case generally on the back of the case but sometimes on the right hand cover well the serial number anyway the model is fairly self evident it's branded on the front like Compaq Evo N1000 or Acer Aspire 1350 something not easy to miss. Depending on the maker the time required to get a product key will vary some may be able to give you one immediately and others will have to track down the correct product Key for that Box which may cost you but no where near as much as a new copy of Windows.
If you have a White Box without a COA and the install CD doesn't have a Hologram on its front you most likely have a Pirate Copy of Windows in which case you don't want to ring MS as they take a very dim view of this practice.
However if it was sold that way and you have proof you can contact MS's Anti Piracy Hot Line and report it once if you helped them to stamp out Piracy they would replace Pirate Copies with Genuine Copies of the Software involved but it required far more than just saying I have a pirate copy here what are you going to do about it? You actually have to have proof and a paper trail back to the original Shop where the system was bought and I'm not sure if MS is still doing this as I don't deal in Pirate MS Software.
Col
