KnowWonder redeemed itself with the release of Chamber of Secrets, a vast improvement over the first game: finished graphics, decent voice-over (Harry speaks!), the ability to explore Hogwarts after learning new spells and the story (although the final battle against the Basilisk is a bit rubbish since Fawkes doesn't scratch the thing's eyes out). Other additions, include Dueling, spell challenges with time limits and the ability to take them again if you're a completionist, the Bonus Beans Room where you need to pick as many Bertie Bott Beans as you can, and the expansion of collecting Wizarding Cards in order to unlock a Golden room on the first floor. For those HP fans or gamers who complain of graphics and gameplay, this is the one you should start with.
P.S.
A year later, Warthog Games' dreadful Philosopher's Stone game for the PS2 copied most of the spells from this game considering it was released over a year after CoS.