Western Digital Caviar Blue 640GB 16MB Cache Interal Hard Drive for $49.99 Shipped

Western Digital Caviar Blue 640GB 16MB Cache Internal Hard Drive for $49.99 shipped after coupon code BEACH5.  Here is a screenshot for reference.  It uses a high-density 2-platter design for better performance while reducing power usage.  Note that it comes in OEM packaging, which means no pretty retail box but is otherwise identical.  It usually goes for about $56 or more.