Full drive encryption is meant to protect against theft or loss, not against trojan horses (be that hardware or software). To protect against trojan horses you

Full drive encryption is meant to protect against theft or loss, not against trojan horses (be that hardware or software). To protect against trojan horses you need an external validation mechanism or a physical protection (be that a safebox or TPM, by the way the Truecrypt team is wrong about TPM, it's much more difficult to temper than bytes on a hard disk).