External hard drives provide storage space in addition to the space on a PC's internal hard drive. Many people use external hard drives to secure, or backup, files they may already have stored on their computer's hard drive in case their internal drive crashes.

Although, some people may use externals simply as additional storage space for files they don't want bogging down their PC drives, or transferring files from one computer to another. The best external hard drives range from about $80 to $500, based on storage space and performance.

For those of you that live by the motto, "go big or go home," there are a couple options for you. The CMS Products V2 Desktop Backup System 1TB holds 1 terabyte of storage space, that's 1000 GBs! The CMS external is no featherweight; it weighs in at almost 5 pounds, but PC World gave the storage unit a 100 on performance and it's large storage capacity makes it worth its near $200 price. Its lack of mobility is really the only con.

Western Digital also offers their version of a 1 TB external called My Book, that comes in black or silver; it's less expensive then the CMS drive and lighter. My Book ranges from $120-$160, has MAC and PC versions, and has garnered rave reviews from customers. Most casual PC users will never need 1000 GBs of storage space, so there are other more mobile, and even less expensive options for you.

The Seagate FreeAgent Go external hard drive provides 320 GB of storage, plenty for the average computer user. The FreeAgent Go for PCs is about 2 inches thick, weighs just 9.6 ounces, and ranges from just $70-$90. Seagate also offers a version of the FreeAgent Go for those of us Apple folks. The MAC version is about an inch thicker and costs aroundt $120, but it's touted as being highly energy efficient and it includes a desktop dock for easy set up. The FreeAgent Go for MACs won the MacLife's Editors' Choice Award in December 2008.

The larger external hard drives like the CMS Products V2 Destop and the Western Digital My Book are great buys for those that store a lot of big files, like a lot of professional photography, graphic designs, flash files, web-design, or video. But for the average consumer something smaller that stores 250-400 GB is all you'll really need.

Most of us just use our computers to listen to music, share a few personal photos, and store some of our favorite movies. The best external hard drives for those of us are those offered by Western Digital or the Seagate FreeAgent Go series that hold 250-400 GB. Both companies' provide more than adequate solutions to backing up files or storing stuff that you don't access that often anymore. Although you may not think you need an external hard drive it's a very affordable way to ensure that you'll never lose your most important files and documents.