Whole Disk Encryption For Vista?

Q7U writes "After reading about several laptop thefts and losses, my boss wants me to set up whole disk encryption for her Vista travel laptop. After doing some research, it seems she has three options: Bitlocker (part of Vista Ultimate), PGP Whole Disk Encryption, and TrueCrypt. My main problem now is choosing one. I can't find any comparitive reviews of these products to determine which will be the best choice, so I was hoping the Slashdot crowd could suggest which product they would go with and tell us what they liked about their choice."