I have a HP 6510B Notebook that came preinstalled with "Windows Vista OEM Business ACT), at least this is what is printed on a label pasted on the underside of the notebook. To get a clean install I formatted the system and and am now tryignj to reinstall Vista using the Windows Vista Free Direct Download Link. When prompted for the product key, I'm entering the one printed on the label, but Windows says that the key is invalid. Is the OEM DVD different from what I got above? Thanks.