Converting dvd files to ISO

I started 5 years ago backing up my dvds to HDD.  I ripped them all to dvd files (.ts .vts and .vob ext).  In the last year I found WD Live and like the technology but never fully used it because of the quirky nature of the playback.  I recently started backing up to ISO files after reading some of the suggestions from the forum.  I love the playback from the ISO files.  Its like night and day.  Even my kids can use the Wdlive now. 

My issue now is I have 1.5 Tb’s of dvd files on my Nas server and want to covert them to ISO.  Doing them one at a time is going to take forever.  Does anyone know a good program I can use to convert my files to ISO.  Preferably free software.   

A good free program to use is ImgBurn by Lightning UK (the same guy that wrote DVD Decryptor).

You can use some kind of batch file with ImgBurn which should speed up things. Dunno if he has implemented an automatic setting of layer break in the meantime though.