If your multimegabyte music, picture, and video files have your current hard drive bursting at the seams, it may be time to upgrade. Today, high-capacity hard drives are more convenient than DVD drives, and they have become amazingly affordable--a 200GB drive can now cost less than $100. Hard drives are a breeze to install, with a few minor caveats. Here are some important things to consider before you pop your PC's hood.

To use a hard drive larger than 137GB, your computer's operating system and BIOS must support 48-bit logical block addressing (LBA). This refers to the number of sectors that a PC can recognize on a hard drive. The 24-bit addressing used by older hardware and OSs limits the amount of data they can recognize on a single hard disk to 137GB.

If your PC is more than two years old, its BIOS may not support 48-bit addressing. Consult your user manual, or contact your computer manufacturer to determine whether the system needs a BIOS upgrade.

David Marcionek's $10 downloadable HDINFO utility tells you whether your BIOS can handle big hard drives. Marcionek's site is filled with useful information about how to add a large hard drive to your PC.

Drive Considerations

If your PC's BIOS doesn't support big drives, you have a number of options.

Update your BIOS: Check the vendor's Web site for BIOS updates. If you find one, follow installation instructions to the letter. A BIOS is a terrible thing to trash.

Use the drive's DDO utility: Most big hard drives come with a Dynamic Drive Overlay program (Seagate's DiscWizard and Maxtor's MaxBlast are examples) that performs the needed initialization by augmenting the BIOS code.

Add a SATA adapter: The easiest but most expensive way to bypass your PC's BIOS limitations is to install an adapter that supports large-capacity drives. The Serial ATA RAID 1210SA card from Adaptec accommodates two Serial ATA hard drives and costs $75.

Drives larger than 137GB also require an OS that supports 48-bit addressing. Windows XP with Service Pack 1 or later and Windows 2000 with Service Pack 3 or later both qualify. With 2000, though, you may have to alter a Windows Registry setting. Download a copy of David Marcionek's EnableBigLba. Run the program to determine whether you need to change the Registry (see FIGURE 1), and how to do it.

If your PC runs Windows 98 or Me and uses an Intel 8xx-series chip set, you may be able to use a big drive by installing the free Intel Application Accelerator (IAA) utility, which replaces the ATA drivers in those OSs with updated versions that support big hard drives. At Intel's site you can download IAA and Intel's free Chipset Identification Utility, and view a list of the chip sets IAA supports.

If you have to buy a new adapter, consider a SATA card such as the Adaptec model I cited previously; you'll have to get a SATA drive, but it will be faster than its parallel ATA counterpart and easier to install. You can also reuse the drive in your next PC. (Note that a drive with a large buffer will speed up the transfer of big files.) For our reviews of massive drives from last March, see "Monster-Size Storage." For instructions on installing a SATA drive, see Stan Miastkowski's September 2003 Step-By-Step column.