I don't know about the 64-bit version of windows, but the game should work fine on any 32-bit version of windows.
The original creator of Castle of the Winds now gives this game away as freeware. you get download it from their site here. http://www.exmsft.com/~ricks/
Download the zip, and extract all files to a new folder called "Castle of the Winds" the zip contains theoriginal shareware version, and the full registered version. Just double click the castle1 executable and go.
If the 64-bit version of windows 7 fails to play this game, then follow the instructions linked in the post above mine. Download DOSBox, then install win 3.x into dosbox, and play the game from that.