To transfer your NYC recipes to a new computer or hard drive, use File... Zip Cookbook... to zip up each of your cookbooks. NYC’s File… Zip Cookbook… operation will include all relevant index files for your cookbook in the .zip file. Then copy each cookbook's .zip file from the NYC \user folder on your old computer to the NYC \user folder on your new computer. Then run NYC on your new computer and use File... Unzip Cookbook... to unzip each cookbook.
Alternatively, you can copy the *.gcf, *.idx, *.cdx, *.cli, *.tag, *.ima, *.imx, *.rli, and *.rdx files for each cookbook from your old \user folder to your new one.