You won't get fog on XP if you haven't got the graphic card that suit's, my first XP with a Nividia card was fine, with my refurb XP no fog at all, this card I have got isn't Nividia
I've got Win7 64bit home and can't get fog. I've done what EG suggested and have started it in administrator and XP compatibility mode. Still not getting fog. what tweaks did you do to your graphics card? I have a NVIDIA GeForce 9400 GT graphics card.