As for Western Digital warranty, take it from them:
Western Digital has adopted a new warranty policy effective October 1, 2002. Western Digital WD Caviar Special Edition hard drives are covered under warranty for a three-year period. All other Western Digital products will be covered under a standard warranty for a period of one year. Products purchased before October 1, 2002 are covered under the product's original warranty, unless otherwise noted on the retail packaging.Maxtor created the three year warranty, and they were the first to bite the bullet and rescind it. Everyone else followed in both cases.
Certain distributors in certain countries are "enhancing" the one year warranty, but it's the distributor's warranty, not the drive maker's.