I use bestcrypt, which seems to be pretty good. Fast, transparent, and reliable.

By the way, if you're really paranoid, don't use DES (obviously), or AES. According to a cryptographer friend of mine, AES has significant holes that are just now coming to light. He recommends 448-bit blowfish as being one of the more secure systems. He also said to keep the partition size to less than a gigabyte, which makes decryption attacks less successful in any case.

Pca