Newegg has Western Digital Caviar Green WD5000AADS 500GB 32MB Cache SATA for $49.99 + free shipping.
IntelliPower - A fine-tuned balance of spin speed, transfer rate and caching algorithms designed to deliver both significant power savings and solid performance.
IntelliSeek - Calculates optimum seek speeds to lower power consumption, noise, and vibration.
Perpendicular Magnetic Recording (PMR) - Employs PMR technology to achieve even greater areal density.
Low power spin-up - WD Caviar Green drives consume less current during startup allowing lower peak loads.
Advanced power technology - Electronic components deliver best-in-class low power consumption for reduced power requirements and increased reliability.
Western Digital Caviar Green WD5000AADS 500GB 32MB Cache SATA $49.99 FS 
