The process of choosing a digital video recorder is complex and fraught. They can be standard definition or high definition, hard disk or DVD based, single or twin tuner, and with plenty of other distinguishing features. Thomas Bartlett shines a light.

At its core, a digital video recorder (which we will call henceforth a DVR to save my fingers from wear and tear) does one simple job: it records a digital TV (broadcast or cable) so that you can watch it later. So we can define a DVR as a device with a digital TV tuner, and some recording medium. The great majority use a computer-style hard disk drive as their recording medium.

To have a hard disk or not to have a hard disk?

As I write, this question is somewhat moot, but that won?t be for long. Presently, all DVRs have a hard disk, but you can be confident that within a year some will use recordable DVDs as their media.

We are not including standard DVD recorders as DVRs, because they have only analog TV tuners, and so disqualify themselves from consideration as fully digital devices. But there are a small number of new DVD recorders with digital TV tuners. All these also have built-in hard disk drives, so in normal operation you would record to the hard disk, and only copy your recordings to a DVD if you decide you want to keep it.

When digital TV-equipped DVD recorders without hard disk drives become available, avoid them unless you wish only to record TV material very occasionally. They will be far less flexible, and with the price of hard disk drives falling so precipitously, not that much cheaper.

All the other DVRs have a hard disk built-in, because that is their sole method of recording, and are referred to as PVRs, personal video recorders.

That may be a troubling concept. After all, what if you?re a bit slow in watching your recordings? Your DVR?s hard drive will eventually fill up, and you?ll have to delete something to make space for a new recording. But, as we shall see, some of these devices have ways of delivering your recordings to a computer, so that you can burn them to a DVD.

With a massive 250GB hard drive and two HD tuners, LG?s LST-5403P allows up to 30 hours of video recording. Price: $1,449.