vista ultimate

my mate has had a problem with his comp so i put my copy of vista ultimate on it which is a oem version.the problem i have is that it is telling me that the product code is being used.is there a crack that works for this or would someone give me a serial number that works.or am i missing somthing as i thought oem ment you never needed a serial.i have placed this copy of vista on mine and my laptop with no problems.any help would be good.pm if you choose or post your comments on here and thanks for taking the time to read this

An OEM installation is a single liscense that a distributor like the store that you purchased the computer from uses. They install it on one computer and then give you the OEM disk. That liscense key once used is locked to the computer it was first installed on.

Here is a link to a Vista Ultimate crack I used on my second computer. The instruction are in the .zip file.