Well, I completed the word racer generator / solver. Boy, the method of keeping the dictionary in a tree is surely fast when searching.

For example, a 20x20 grid which contains around 400 unique words gives a total time of loading and generating the list of existing words of .. 0.2 seconds. Yes, it's true : 0.2 seconds.

The test machine was a Celeron at 1.2 GHz with 256 MB RAM. I wrote the program in Visual Studio 7 and succesfully and errorless managed to compile it in g++.