We just built a house (Jan 05) with hardwood floors (strips). I have noticed numerous cracks (almost every or every other strip) throughout the area. The cracks are large enough to put a dime in (and in some areas a quarter). I am reading that the floors will expand in the non heating season, but on older floors - not brand new. What info. do I need to know?

All floors expand and contract with changes in relative humidity. Age of the floors has nothing to do with it. If the floors were installed in the fall or late summer before the heat was turned on, you may be experiencing winter shinkage due to the lower humidity caused by heating systems. The flooring may not have been properly acclimated. Check with the flooring company/installer who did the work and ask for an inspection. You should probably go through a full weather cycle before determining if there is a problem (the cracks may close up in summer). You may need to increase the humidity levels inside during the winter months.