Believe it or not, I actually own a tape drive. For a while, I was doing religious backups, but that stopped at some point. The last full backup I had done was about two months out of date and had none of the audio that I had produced for "The PhoneBoy Chronicles." So I'm out of luck anyway.
Regular backups are a necessary part of computer maintenance and should be performed on a regular basis. The frequency of backups will depend on what you use your computer for, how "critical" the data is, and how hard it will be to re-create the data should a failure occur. There are two types of backups: incremental and full. Incremental backups are just "changes" that have occured since the last full backup, which should contain everything on your system.
The first one is tape. These days, they make tape drives in all shapes, sizes, and price ranges. Tapes and tape drives usually have two sizes associated with them: compressed and native. Usually, it will be the "compressed" size that is in bold letters, and it will be twice the size of the "native" size. For instance, my Ditto Easy 800 tape drive writes on TR-1 tapes, which store 400 megabytes worth of information. If this data is compressed as it is being written to the tape, it will most likely store more than 400 megs worth of information, but probably less than the 800 megabytes that they say the tape can store. When you buy a tape drive, make sure that you buy it based on it's native, or uncompressed capacity. Your tape drive size need not necessarily equal your hard drive size, but if your hard disk space is bigger than the capacity of your tape drive, you will need multiple tapes to do a complete backup of your hard disk.
Tape drives vary in the amount of space they store and in the cost of the tapes. A Ditto Easy 800 costs around $100 with TR-1 tapes around $30. The new TR-4 tape drives cost around $400 and the tapes cost around $60. Most PC-based tape drives will either hook up to your floppy drive port or, in the case of the higher-end tape drives or tape drives for the Mac, hook into your SCSI bus.
The second option is some other form of removable media. Iomega and SyQuest make the two most common forms of removable media. The Zip drive, made by Iomega, allows you to store 100 megabytes of data on a single Zip disk. The Zip disk is very similar to that of a floppy disk both in design and in usage, though Zip disks are faster and hold more data than your average floppy disk. The Zip drive, which hooks into your parallel or SCSI port, is about $150 after rebates. The Zip disks will cost you about $15 each, though you can get them in packs of 5 or 10, which reduces the cost per-disk.
SyQuest makes similar sorts of drives, though most of them will only hook into a SCSI port. The drives themselves will hold anywhere from 44 megabytes to 270 megabytes (depending on the model), and the cost of the drives vary. The media and the drives are more expensive than the Zip disks. The SyQuest cartridges are actually more like hard drives than floppy disks, which adds to their cost.
The Jaz drive, also by Iomega, stores 1 gigabyte of information on a single cartridge. It's much more like a SyQuest drive in that the cartridges actually look and act like hard drives in many respects (including speed). The drive is $500 and the cartridges are around $125 each.
Zip drives are somewhat faster and more convienent than Tape drives at accessing data, but they too have a bottleneck -- the Parallel port. Backing up will be faster, but restoring will be slow. Some speed can be gained by using the SCSI version of the drive. Cartridges for the Zip drives can be purchased in packs of 10 for $100, making the price per megabyte roughly 10 cents. A little more expensive than tape drives and not great for storing large amounts of data.
If you want fast access to your data and the ability to back up a large amount of data, the Jaz drive is the way to go. It's as fast (if not faster) than your hard disk. It stores a gigabyte of data on a cartridge. The price per-megabyte is as cheap as the Zip drives. The downside is that you need a SCSI card to use the Jaz drive and the Jaz drive is more expensive than a comparable tape drive.
For many home users who make few to no changes to their computers, weekly incremental backups and monthly full backups should be adequate. Heavy users may wish to do daily incremental backups and weekly full backups. A full backup should also be done before any major changes occur on your system. A major system change includes -- installing large applications, updating your operating system, or adding new hardware. A lower-end tape drive or a Zip drive will suffice for most home users.
The important thing is: once you make a backup schedule that suits your usage patterns, stick to it. Do it religiously. And use at least two sets of tapes, alternating between the sets each time a full backup is performed. For example, let's say I want to do full backups weekly and incremental backups daily using two sets of tapes. The number of tapes you will need for a full backup will vary depending on the size of your tapes and the amount of data you will be backing up, but in most cases, you can usually store multiple incremental backups on the same tape. So let's say I need two tapes to do a full backup and one tape to store my incremental backups on. I would run my full backup on two tapes and my incrementals onto another tape. When it's time to do my next full backup, I switch to the other set of tapes. This way, I have two weeks worth of changes to the system, plus two complete snapshots of my system. Just in case something goes wrong.