If you are able to find the product number of it that would be useable, the serial number is only used by gigabyte.
Either way, the drivers available today are "all-in-one" for vista/win7. (Usually only separated by 32 and 64-bit versions.) Just download and install
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(I'm assuming you at least know if your card is AMD/ATi or nVidia)
The link below will take you directly to the download page for the AMD/ATi drivers you need
http://support.amd.com/us/kbarticles/Pages/Catalyst121Previewdriver.aspxThis link will take you directly to the download page for the nVidia drivers you need
http://www.geforce.com/Drivers/Results/40608Hope this helps you. Also, these drivers are the beta versions, but I can't personally advise anyone to use the older release drivers.