James, you say you have ventilation holes in the top of your tent. Don't cover them. They let moisture escape, and allow air to move in the tent. This will aid in keeping condensation from forming on the inside of the tent. I wrap a warm jacket around my feet and wear a stocking cap when I go to bed, in a sleeping bag. As the others have said, a good pad or something underneath you will work wonders at keeping you warm.
Phil.
"Could you guys be quiet, my dad's trying to shoot."<img src=icon_smile_shock.gif border=0 align=middle>