Hi, I've been trying to think of the name of a game I used to play on
an old PC, I think with Windows 3.1. In this game, you are given a 2-d
box with different shaped blocks inside (squares, rectangles, and odd
shaped polygons). One of the blocks is a different-colored key block.
The goal is to rearrange the blocks to get the key block to the box's
exit, and into the goal spot outside. I remember that there were 3
difficulty levels to the game, and many many puzzles to solve. I
didn't buy it, so it might have come with the computer or be
shareware.

I feel like I'm so close to thinking of the name, but I can't, and
it's driving me nuts!  : )  I would like as an answer the name of the
game and possibly a link to more information about it - when it was
released, where it came from. A place to download it would be extra
nice. Thanks!

The game you are looking for is Klotski.  It is of Russian origin.

More info here:  http://en.wikipedia.org/wiki/Microsoft_Entertainment_Pack

D/l can be found here:  http://phil.freehackers.org/klotski/

Enjoy

Klotski!  Thank you so much!