Lately, this type of question has gotten a LOT of attention. So, for the benefit of those who've already responded to this type of question a few times, I'd like to offer them a 'break'.
Use your WEB Browser's FIND (or Search) feature and key the word insulator into the box, and press Find. What you'll get are a LOT of hits where one of our resident experts on insulation has written some responses. 'The Insulator' is the guy you're looking for. Attic Insulation is just ONE of MANY Posts he's addressed. Other keywords you can search on are fiberglass or even cellulose.
Good luck! If you still need help, post up. My best to ya and hope this helps.
Jay J -Moderator
PS: It's 'that time of year' that draws a lot of folks like yourself to ask about attic insulation ... ;-)