Sudoku craze

The local paper added Sudoku puzzles this week. Reportedly, the puzzles are popular in Japan and Britain...and the craze is spreading worldwide. I'm pretty sure I've seen similar puzzles before. The concept is simple: using the numbers 1 to 9, complete a 9x9 grid, comprising 9-3x3 squares, without repeating numbers in any line or 3x3 square. The puzzles require logic, patience, and a good eraser!