Seagate new Barracuda XT isn't the first internal hard drive to reach the 3TB plateau, but it does make it easier to access all of that storage if you are still using Windows XP or have a system with a PC BIOS controller.
The problem for those with such legacy technology is that they don't natively support storage beyond 2.1TB, which means there's little purpose to buying a 3TB drive if you're losing almost a third of that capacity. Seagate has devised a software workaround in the latest version of its DiscWizard utility to let XP and/or PC BIOS desktops access the full 3 terabytes. Essentially, DiscWizard sets up a device driver that it manages (not Windows) for the drive's storage above 2.1TB.
If you have a newer desktop with a UEFI BIOS controller (and Windows Vista or Windows 7), it can handle 3TB natively, but Seagate has you covered, too. It spins at 7,200rpm, features a 64MB cache, and makes use of the Serial ATA 6Gb/s interface.
Online retailer Provantage.com is showing the drive for a shade under $270, which isn't cheap, but they'll be some out there willing to pay for that massive amount of storage.