You're in North Carolina, right? How cold does it get?
Insulation, by itself, does not make an area warmer; it just reduces the flow of heat. The earth, itself, is a source of some relative heat. Some insulation around the top of the crawl space should keep temps above freezing.

__________________
1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags