Just had a project at work for this exact subject. We chose PGP's Whole Disk encryption for the individual laptops, seems like the retail was like $150 a seat, but I think it can be had for much less online.

TrueCrypt is the best if you want to make an extra drive (ie: D: drive) on your laptop that is your "encrypted" drive. On work machines I used TrueCrypt (it's free, too) and keep all my work stuff on the "open" regular C: drive and personal stuff like family phone lists or whatever I keep on the encrypted "D:" TrueCrypt drive.

PGP was the best solution for someone that wants 100% of the laptop data useless if stolen and the Enterprise version allows the help desk to give a user a temp password if they forget their boot password. Well done product.

There are other products I had to review for this project but it came down to these two - PGP Whole Disk for the complete full-disk encryption, TrueCrypt for the "additional drive" type volume encryption.