. . . you need to make sure that your game is fully updated to v1.2, and then apply either Mok's patch, or Grayface's. I've not played games with Grayface's patch, but as I understand it, Mok's patch just enables you to play the vanilla game smoothly, whereas Grayface's changes the game in a few places –I don't know where. Mok's patch was, however, originally designed to enable the games to be played with WinXP as the operating system, so you might need to fiddle with the compatibility settings as well.
Try it and see, and if it doesn't work then get back to us.