We needed to put full disk encryption on our new company laptops in case they get stolen. To be honest, I think EVERYONE needs to do the same. Honestly, in this day and age, there is no excuse for unencrypted hard disks. You might not know (but you should) that unencrypted hard disks can be plugged into another machine and read without needing a password or anything.
Anyway, I thought we had Bitlocker because we had Windows 7 professional but it turns out that it is Win 7 Ultimate that has Bitlocker. I turned to Truecrypt which is free and fully featured, it turns out that it handles full disk encryption as well as the ability to encrypt individual drives or folders. I followed this guide and it was all sweet: http://www.ucl.ac.uk/isd/common/cst/good_practice/encrypt/FullDiskEncryption