As a big fan of open- source software, we were hoping that TrueCrypt would give the commercial products a run for the money not spent. Unfortunately, TrueCrypt is not really whole drive encryption software as it was defined for this category.
TrueCrypt can encrypt an entire drive - however, that drive cannot be the drive from which the operating system boots. TrueCrypt is capable of encrypting external USB drives, flash drives and MP3 players, but it cannot encrypt the partition on which Windows XP resides.
The installation was quite straightforward, and the documentation was written well enough so that we could determine in just a few pages that TrueCrypt was not able to perform entire disk encryption in the way the other products in this category could.
A quick Google search yielded a support page for TrueCrypt. This explained why it could not encrypt the operating system hard drive: the product does not have a software agent that would interrupt the boot process to require authentication for the encryption software to decrypt the drive.
TrueCrypt's documentation mentions that this functionality may be coming in a future release, so it may be a case of watch this space.
This product is good at what it does in terms of encrypting external (non-boot) drives, but as far as protecting your operating system, this open source offering just does not have that ability yet.
Since the software is free, it does provide good value. In addition, if you are operating on a thin budget, TrueCrypt is the best option for file encryption.
Many users create a boot partition that, perhaps, contains applications along with a second partition for data only. That part can be fully encrypted using TrueCrypt, or you can create encrypted containers for various folders.