There are four ways to get access to more than the basic five channels screened nationally. Digital television is available through Sky itself, using a satellite dish and a decoder, or from cable companies such as NTL and Telewest, which run a cable into your home, as long as they have connected up your street. Then there is Freeview, for which you simply need to buy a new set-top box to connect to your existing TV aerial. The final option is the newest entrant - companies such as HomeChoice, which provide digital television through a broadband internet connection.
Bear in mind that with Freeview you can only access a limited number of free-to-air channels. These include services such as E4, BBC News 24 and Eurosport. This may be all you want, in which case Freeview can be cost-effective.
Alternatively, Top-up TV is a relatively new service that works with a Freeview box. On top of the Freeview offer, it gives you access to around 10 additional channels - the Cartoon Network, for instance - for £7.99 a month. But you won't be able to access the Sky channels this way.
For these, you need digital cable or satellite television, or an internet-based provider. These other services work on a similar basis - for a fixed monthly fee, you get a small number of basic channels. You then pay extra for the Sky Sports channels, the Sky Movies channels and any other premium channels you require. Special deals are usually available if you want a mix.
It is important to decide whether TV is the only digital service you're looking for. "There's been a real shift over the past couple of years," says Chris Williams of online price comparison service uSwitch. "The cable companies are now primarily pushing broadband internet access and selling digital television and phone services on the back of that service."
Telewest and NTL offer digital television as part of a bundle of services - the same is also true of the broadband-based entrants, such as HomeChoice. Telewest claims bundling up will save you money - up to £420 a year, depending on which providers you currently use for digital TV, broadband and a phone service. But Williams says there are pros and cons to this approach. "For most people, this is not likely to be absolutely the cheapest option - you'll make a saving by sourcing each service individually - and you are also likely to be tied into a 12-month contract," he warns. "On the other hand, many people will be very attracted to the idea of getting all these services in one convenient package."
Service is the other issue to consider when it comes to choosing a digital television provider. "All the evidence is anecdotal, but it is generally accepted that the cable companies have been less good on customer service levels," says Williams.
Finally, bear in mind that by 2012, all of the UK's television transmitters will have been converted to digital. At this stage, the analogue signal is due to be switched off, so everyone will need to have a television that is digital friendly. And before you, say, upgrade to Freeview, the cheapest way of going digital, check the position in your local area. In some regions, a lack of digital transmitters could mean poor picture quality and sound. You could be forced to shell out for extra equipment to get a decent reception until your local transmitter has been upgraded.