Any freeware that compresses an entire hard disk onto 2 dvds for backup?

There isn't a compression algorithm good enough to compress that much data. There is a physical restriction on the amount of data one can fit on a DVD (about 7GB). Today's hard disks are typically larger than 100GB, which means you'd need a compression ratio of greater than ten-to-one. Since many files don't lend themselves to compression (which is achieved by eliminating duplicate data bits), you could only do this if every file on your hard disk was a simple text file. And even then I doubt it.