Billy - Make sure, when you add insulation to attic, that you maintain
proper ventalation. See
http://www.factsfacts.com/MyHomeRepair/ventilation.htm for discussion
about attic venting. If you have vents, don't block them. If you dont,
consider adding them. The vents will help keep you house cooler in
summer, prolong the life of the roof and prevent ice dams. They will
not negatively affect your heating capacity if done properly.