In real estate, they say you can never have too many closets. On your PC, you can never have too much hard drive space. Whether your current drive is topping out or you want the security of a RAID array with automatic data backup, there are always good reasons to install a new hard drive.

We've got answers to some of the main questions about this upgrade, plus step-by-step instructions. If you'd like to see the process in action, check out our video, How to Install an Additional Hard Drive.

If you're interested in RAID, read "Make Your Hard Drives Faster and Safer With RAID" or watch our video, How to Install RAID.

What Kind of Hard Drive Should I Buy?

Bigger is always better--but shop around for the best values. Sometimes two drives can deliver more storage per dollar than a single larger drive. For advice on buying a new drive, see "How to Buy a Hard Drive."

Whenever possible, buy a hard drive that uses the Serial ATA interface; SATA's thin cables and one-port-per-drive design are a vast improvement over older Parallel ATA drives and do away with PATA's master-and-slave configuration nightmare. If your PC lacks SATA ports, spend the extra $30 to $40 for a SATA host controller card; that way you can use your new hard drive on future computers.

To date, we haven't seen much of a performance difference between SATA 150 and the newer SATA 300 hard drives, so don't feel compelled to pay more for the newer technology.

If you're adding an additional drive to your PC, make sure you have an open drive bay inside your case. If you don't, consider getting an external hard drive that connects via a USB port or an external SATA port. If you have an extra internal drive and no room in your case, you can create your own external drive: Several companies like Addonics make housings for this purpose.