People tend to concentrate on either image or sound. Generally speaking, we're exposed to the image side of things more. It's easier to set up tens of TVs one beside another in shops than a wall of speakers. Nevertheless, a sound track is vital in terms of drawing you in to a film and shouldn't be neglected.

All-in-one or separates?

There are two types of system: all-in-one package systems or separates. The advatage of the all-in-ones is that they're generally cheaper, take up less space and are often better designed to suit your decor than large floorstanders. Separate speaker packages give modularity however and the option to develop your solution almost endlessly. Indeed, if you go for a separate player, amplifier and speakers, you can replace them one at a time and spread your spending.

Think about the set-up!

Going for separates brings modularity, sure, but also a number of problems. While linking your Blu-Ray up to your amplifier won't pose any compatability problems, linking the amp up to the speaker system is another matter altogether. You must, for example, at all costs avoid choosing an amp that isn't powerful enough for your speakers - they wont last anywhere near as long. And don't take tech specs as gospel! Measurements aren't especially standardised and it isn't always easy to make the right choice.

Is a subwoofer really necessary?

This isn't a trivial question, quite the opposite. There are two very different possibilities. Systems with small satellite speakers or "bookshelf" speakers don't reproduce the bass frequencies properly. Forget what it says in the spec, it may well claim a frequency of from "20 Hz - 20 kHz", the difference in reproducible volume between a sound at 50 Hz and another at 1kHz is such that the bottom of the spectrum will be missing in the majority of cases. Here then, the subwoofer is indispensable, especially for home cinema usage. If, however your system includes floorstanding speakers, you may well find you don't need a subwoofer. With the membrane area you get with these, they're much more effective with bass sounds. Make sure you get information on product capacity before you buy. In fact, a film enthusiast will often require more bass than a music lover. Everything depends on your requirements.

Listen before buying!

Don't trust the numbers and don't buy anything blind. Have pity on your ears and before you go and spend several hundred pounds on a 5.1 system, go and listen to it. Go into your local Home Cinema/Hi-Fi shop and have a listen to a selection of systems. Even if you're going to buy on the net, this way you'll avoid any nasty surprises - personal taste also comes into things and you need to find out what suits your ears!