I use Exact Audio Copy.
http://www.exactaudiocopy.org/
It is one of the best, if not the best, to do the job. You will need to set it up to rip to FLAC, but it's not too difficult. Check out this site and follow the directions for setting up EAC with FLAC.
http://users.pandora.be/satcp/eac-qs-en.htm#flac
Good luck.