The 7200.9 range of Seagate drives covers capacities from 40GB up to a massive 500GB with 2, 8 and 16MB buffers.

The Barracuda 7200.9 ST3500641AS is one of the 500GB capacity four-platter drives and comes with a 16MB cache, a 7,200rpm spin speed, NCQ (native command queuing) and is one of the few drives around that has the new Sata (Serial ATA) 3Gbits/sec interface (capable of a 300Mbytes/sec transfer rate).

There is also a Pata (Parallel ATA) version (model ST3500641A) for those without a Sata interface.

The drive does get warm while in use, so make sure there is good ventilation in any case in which you use the disk.