Rybka 4 or Houdini 3

I want to buy either rybka 4 aquarium or houdini 3 aquarium.

Which one should I buy?

I am leaning towards Rybka 4 because I have used Rybka 3 aquarium in the past(which I no longer have), and I liked the 'flavor' of its analysis.

but i have not yet seen houdini 3.

Also, I am mainly interested in its IDeA feature(Interactive Deep Analysis), whereby you can guide the analysis towards certain lines and the moves are visible in a tree form. Has anyone used this feature and is it all that it is hyped up to be.

I see no point in buying Rybka 4.

You either want to have the very best, in which case you will want to get Houdini 3.

Or you want to get the best deal, in which case you will want to get Critter and/or Stockfish as they are free and stronger than Rybka 4 at the same time.

Your main interest seems to lie in a feature of Aquarium (Or at least that IDeA-thing sounds like it is a feature of the GUI, not the engine). I don't know if you can get it without engine. If you can only get it with an engine, and the Rybka-version is significantly cheaper, than that would be the only imaginable reason to get this one instead.

For the average chess player, buying either one is in my opinion a complete waste of money. Stockfish is just marginally weaker than houdini and stronger than ribka, and completely free. If you just want to analyze your games you will never notice any difference in strenght between stockfish and houdini. If instead you're a titled correspondence player playing against equal opposition, then it would make sense to invest money on houdini.

Why would a titled correspondence player want the very best engine? I thought engines are not allowed. Not that it would surprise me in the least though. Thats why I have no interest whatsoever in correspondence/online games. I'm sure most people use engines. Why dont they just call in Centaur games and be done with it? Still need a lot of skill, I guess, to beat someone with an equally strong chess program.

I was referring to real correspondence chess (the one played on ICCf or LSS for example) where computer assistance is allowed. Of course you don't need it to play online chess here. Anyway you shouldn't worry too much about computer cheating here; it might become in issue only if you break 2000, and even then it's pretty rare.

You don't need to buy any engine the free ones are more than adequate for players like you and me.  You can also get free versions of Houdini 1.5, Rybka 2.2 etc that are not the latest & greatest editions but which are still world-class quality. Bresando and Xilmi have the right idea here, pay attention to them.

You do know that an engines performance is maximized in a 64-bit OS where it can utilize a multi-processor CPU right? 

Here's a current list of the best engines and best free engines along with download and home page links.

http://www.computerchess.org.uk/ccrl/4040/

Komodo 5.1 MP is also reliable choise, although H3 is still best.

FirebrandX  no slight intended I didn't read your entire post the first time around just the first part about ICCF. Personally I don't think anyone around here needs Houdini 3 or Rybka 4 for ICCF or any other reason, but if they can afford them and have a PC capable of utilizing their full capabilities I guess there's  nothing wrong with being a "spendthrift" occasionally.

As a final note, I often wonder how many players so concerned about having an engine rated +3000 rather than settling for some piece of crap rated a lousy 2900 know if their OS is 32 or 64-bit and what a multi-processor is?

Good discussion. Any recommendations for software that is useful for saving lessons from chess books. I am wanting to load endgame and middlegame positions from books and then test myself. I appreciate suggestions...

If I have money to spend, I would buy Houdini 3 Aquarium. Rybka 4 used to be the best but It's the Houdini show for the last 3 years. I don't think It's a waste of money. 

Support chess software developers and buy both

Great suggestion, Natalia 

i am mainly interested in the IDeA feature which is available only with aquarium and while i am buying a good GUI, might as well get a reliable engine to go with it.

What makes IDeA(Interactive Deep Analysis) different from normal infinite analysis is that you guide IDeA along certain lines that interest you and the tree is stored on disk so that you can little by little explore almost every line that interests you. it keep building the tree and storing it so that you can let it run overnight and in the morning you can explore the whole tree and then again guide it towards certain other positions you might want to explore. in this way a reliable repertoire can be constructed which is typical only to you.

Then one might want to consider buying some other engine. Both Rybka and Houdini are believed to be rip-offs of other peoples engines.

(Rybka is a modified Fruit engine, and Houdini is believed to be a modified Ippolit/Robbolito... which in turn are modified Rybka 3).

If you want to save book lessons to a DB you're going to have to do the "loading" by typing in the moves (or setting up the positions) yourself. You can load pgn files into most chess software. 

ChessPad is free and easy to use, I used it for yrs before upgrading to ChessBase http://www.wmlsoftware.com/chesspad.html

ChessBase Reader 13 is also free. I suggest starting out with ChessPad first but if you're ambitious start using both and see which one you prefer. This one has way more features than ChessPad

http://www.chessbase.com/Download/download

Thanks NimzoRoy. I will investigate.

 NimzoRoy- I am trying out chesspad and having fun with transferring lessons.  Good recommendation.

Glad to be of service. I also like to transfer stuff from books into DBs which forces me to slow down and pay attn to what I'm reading. You should check out ChessBase's free reader ASAP  to see if you want to "upgrade" right away instead of sticking with ChessPad for awhile. Or at least download and install it for whenever you feel like checking it out.

NimzoRoy: I downloaded the hefty Chessbase. I have worked with it for a few hours. I was able to paste a saved game I created on Chesspad that was saved. This was saved as a 'Layout' and I was not able to reload in Chessbase. I then used   a new Chessbase board and replayed the game and saved it. Again, it went into a 'Layout' file and I was not able to reload into Chessbase for further editing or study. Perhaps I am missing a link here? I understand you are loading games to study into Chessbase and thus you have found the route. Might I ask for your indulgence once more and have a suggestion? Thank you...drfell.

I've never used the free CB reader in question (CB Lite 13 right?), but I was ASSuming it was like an older version I did use (CB Lite 9) which as I recall (not necessarily correctly) had the same interface as the DBs they sell. At the time I think the CB Lite 9 was basically the premium program but was restricted from creating or managing DBs bigger than 20,000 games.

All I can suggest is stick with ChessPad for now and when you feel like it start going thru the help files for Chessbase Lite 13 and look around for FAQs and/or articles about it at www.chessbase.com. You could also post questions in our "Help & Support" or "Chess books - equipment" forum but I think you'll probably figure it out on your own if you want to. 

I'm mystified about the "layout" here. In CB 9 you can either "save" games, or "save as" or "replace" an existing game that's been edited or otherwise altered. The save and save as functions are pretty much the same as in a word processor - or in windows when you go to save a file.

A lot of times using a search engine for questions like yours is actually faster than plowing thru the program's own help file.