A brute force attack is not by definition a "back door".
A recovery CD on the other hand...
If you are used to using PGP then
The GNU Privacy Guard - GnuPG.org is a free alternative that is compatible. There are also free front ends available (I think one called Kleopatra comes with it). I think the only difference is the file extension (it by default creates .gpg files instead of .pgp files).
If you are only encrypting the odd file then bitlocker is overkill (and normally requires an upgrade - do you not need compatible hardware too?). I haven't used TrueCrypt so can't comment on it.