Purchase a premium membership, diamond preferably, and watch the video lessons and use chess mentor. They will help you understand the game of chess much better.
Chess software

Trust me, Chessmaster is the best bang for the buck at your level! Check out my review:
http://www.associatedcontent.com/article/786899/chessmaster_10th_edition_product_review.html?cat=19

For teaching from novice level, Chessmaster is better than Fritz. With Chessmaster, however, you get some features that can harm your understanding.
For example:
After a game with a CM "personality", I see this:
Black wins!
Congratulations! This is your first victory against Guillaume.
You lead this game from start to finish, and played a solid game against Guillaume. Congratulations!
Game type: Dominated by black
Domination percentage: 28%, starting from move 10
Opening used: French Defense / Classical Variation
Best move: 47, Kf4, Increase: 89.96
Worst move: 51, Kf3, Decrease: 90.48
Mate opportunities: 3
According to Fritz 9, 51.Kf3 is the best move in the position, leading to mate in three. More significant is that the best and worst moves are those that affect the result. Chessmaster looks at changes in its quantitative evaluation and cannot communicate the critical turning points of the game.

I have chessmaster grandmaster edicion. It has many excerises for improving, but i am not quite satisfied with analysing. I posted a game against chesmaster.

The study courses in chessmaster with Josh Waitzkin and Christiansen are a must for a novice or intermidiate player. Chessmaster is way better for learning the bread and butter of chess than Fritz. I would recomend Chessmaster 10/10 (ten times out of ten) for a novice or intermidiate player. When you get a rating past 2000 then it's time to go pro with Fritz or Rybka.
i've just asked Santa for Fritz 12 (the cheaper version), hopefully she can get this from Amazon for £20 http://www.amazon.co.uk/Excalibur-Fritz-12-PC-CD/dp/B002MZZSL2/ref=sr_1_1?ie=UTF8&s=videogames&qid=1260785972&sr=8-1
I haven't tried Chessmaster but will probably try and get this as well as only £7.50 http://www.amazon.co.uk/Chessmaster-Grandmaster-Edition-PC-DVD/dp/B001F50TAK/ref=sr_1_3?ie=UTF8&s=videogames&qid=1260785972&sr=8-3. I've tried the chess mentor online and found this useful. Loving the live competition on chess.com, post-match analysis is great way to learn for me.
See you online.

i've just asked Santa for Fritz 12 (the cheaper version), hopefully she can get this from Amazon for £20 http://www.amazon.co.uk/Excalibur-Fritz-12-PC-CD/dp/B002MZZSL2/ref=sr_1_1?ie=UTF8&s=videogames&qid=1260785972&sr=8-1
I haven't tried Chessmaster but will probably try and get this as well as only £7.50 http://www.amazon.co.uk/Chessmaster-Grandmaster-Edition-PC-DVD/dp/B001F50TAK/ref=sr_1_3?ie=UTF8&s=videogames&qid=1260785972&sr=8-3. I've tried the chess mentor online and found this useful. Loving the live competition on chess.com, post-match analysis is great way to learn for me.
See you online.
Here is where I got my Chessmaster from...it's slightly cheaper :)
http://shop.lovefilm.com/games/platforms/pc/chessmaster-grandmaster/9998909.html
I am very much a novice but want to improve. What is the best software I can buy that teaches from novice level? I was looking at Fritz 12 or Chessmaster: Grandmaster but am open to other suggestions.
Many thanks!
Flandaddy