fritz 12 and rybka 4

What is so benificial about having a chess software such as fritz 12 or rybka 4?

Given the right hardware you have a chance when playing other engines.

lol prawn.

To the OP, I've always enjoyed trying different moves and positions then watching the evaluation change.  I'll think up a move I decide is good, then I check what the engine prefers.  Then I'll force it to play my move instead... if the evaluation changes a little then my move is fine and I explore it down that line -- if it changes a lot I follow the line to see why.  Then also follow the computer's line to see what it preferred.  You play a lot of why not this and what about that, after comparing the two lines you figure out the difference and you'll have learned something.

For example you might reach nearly identical positions 8 moves down the road but an extra pair of knights are gone in one line vs the other.  Why are the evaluations so different?  Oh I see, black's knight was a critical defender of an important square, or white's remaining knight is too passive, etc.