I have gotten hooked on this new puzzle game Sudoku. Fiendishly simple (just make sure the rows, columns, and inner boxes each have one instance of 1-9) but oh so difficult to make it happen. Wikipedia has a nice write up on it. I have been playing it on Web Sudoku. The evil level really is that. Make sure to set the option to allow you to write in multiple numbers in one box if you are going to attempt that level.
As Microsoft gets ready to freeze their code for Vista, they need to remember that the old reason people upgrade is for the new game. Minesweeper was the reason to get Windows 3.1, Freecell was a sold reason to upgrade to Windows 95, and Spider Solitare made up for the otherwise worthless upgrade to Windows ME. For Vista, I have two words: Su Doku (or maybe that is 1 word, definitely two japanese characters: 数独).