Nintendo's Wii Fit, which goes on sale next month, is supposed to marry video games with exercise, and it's supposed to be a huge hit. One analyst predicts it could sell 4 million copies in the US this year, and Nintendo is supposedly backing it with a  $40 million marketing blitz.

But what if it turns out that video games and exercise don't mix that well, after all? Well, then the Wii Fit will follow in the footsteps of Nintendo's last attempt to do this: The Power Pad (the image to the right is of the Power Pad's European cousin).

Released in the late 80s, the Power Pad was an electronic mat that was supposed to measure running speed, timing and coordination, and even test your memory. And if that sounds like fun to you, you're in a distinct minority. Nintendo only released a handful of games for the…