There are better ones available for free such as spike turin or toga II.
Chess engines
I believe that the Fruit chess engine is supposed to be quite strong (and it's freeware)! Spike and Toga are also apparently quite strong.

If you are looking for free ones then those have already been mentioned. If you are looking to part with a wee bit of money then I recommend the following:
Chessmaster Grandmaster Edition - I found the game analysis on this to be pretty limited but not sure what to expect from a computer as it can't give guidance like a human can. Apart from that slight weakness, which surely all suffer from, it does give a variety of strengths to play against over optional time controls. I personally set my board up and play against it OTB in preparation for tournaments. It also has some nice learning features as well as a database and openings teacher. I found that unlike some other programs which supposedly weaken their performance, this one does it in a much more human-like way. For instance it won't play very strong and then suddenly throw a rook away, it has realistic weaknesses in different areas of it's game depending on which "character" you play against.
Rybka 3.0/Shredder 11 - Both very strong engines that you can use to look through your games for tactical weaknesses. Although these won't make suggestions on strategy you can usually see where you went wrong and areas you can improve just by looking through a few different lines on each move.
While Chessmaster has some strong points especially for begginers( a great set of tutorials and exercises), it's not good at analysing games.

Disable other features of your pc that takes a lot of memory and program while you are using the engine, applications like programs mininmized, screen savers, pop-ups, anitvirus etc. Make sure you pc is running only the progam that you have to at least maximize the pc playing strenght when using the engine.
Lastly go for a fast pc,fast ram and high memory capacity, faster hard drives if you can afford it.
HEY if your well with money then spend it.However if your like me an live pay ceck to pay check then its your lucky day as there are a lot of good free programs.Look for my post here on in my opinion my top 30 free chess downloads along with 13 good chess engines.lOOK UP ARENA on internet download it then look up Top Uci google it as its a great freeengine russian download site an load the top 10 win engines and the top 25 uci engines have fun an save your money by the way arena aklong with some good chess engines are here on chess.com download site.
I currently have two types of chess engine, both I think quite old - gnu chess and crafty (which came with a program - chess tactics for intermediate players). Still, does anyone know which one is better? I know they are no match for fritz and those... but those are the only two i have to prepare for tournaments and to analyze a game. Which one should I use?