if it is an OEM license I don't think you are technically allowed to transfer it. If it is a retail license then you can. There are tools that will let you extract the key from an existing installation. The legalities of obtaining the install disk are a bit questionable however.
If you are a student of have one in the family you can purchase it
http://store.digitalriver.com/store/...e.SHHomePbPage it's not as cheap as it once was
