What' s the best engine aside from Houdini that is free?

I like Houdini 1.5 but it hogs my computer big time.So what's the best substitute out there?

Now that I'm thinking about it,Houdini 3.0 is the strongest engine.But it's not the strongest FREE engine out there.Houdini 1.5 is the strongest free engine i suppose. or is it?

Stockfish is really good

Try looking here:

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

I tend to use Stockfish and Critter. I use Critter in highly tactical situations and Stockfish in most other situations.

Criter solves tactical problems much quicker. Stockfish clearly understands closed positions better. Both are about the same strength overall.

I have been enjoy playing with ICC free chess engine. You can download it on  http://www.chessclub.com/ . There has many differnt levels. You can play against any level you like. The hardest level will be similar to Houdini. I lost all games playing with the hardest level and couldn't even have a chance to draw.

You can run the engine at "Priority below normal" to prevent this.

See the first FAQ at http://www.cruxis.com/chess/manual/some_frequently_asked_question.htm .