Computers have changed chess over the last 15 years. Today a player can have a chess book in one hand, a coach in one ear and a computer program able to tell him or her the strongest moves in 99% of chess positions. If you're a novice, keep in mind that a computer can't explain things in human language, is average with long-term planning advice (e.g. it isn't great at telling you if you should play on the kingside or the queenside in a game) and that you still need to have knowledge only a book or coach can give you, if you are going to understand why the computer is suggesting certain moves.
A lightweight chess program is the Tarrasch GUI, which you can download here. Once you have installed the software, click Commands - Start Kibitzer, and a strong engine will begin rating the position and offering you the best continuation for each side. The engine gives a "+" score if white is better, and a "-" score if black is winning. The figure (for example - 7) means the computer things that black is the equivalent of 7 pawns ahead.