encryption software-freeware or commercial?

Hello ,

The company I'm working for, a small one, want to have an encryption software (we found on Google about the commercial software from CompuSec, DiskProtect, DriveCrypt Plus Pack...but also Truecrypt) to encrypt the OS partition and protect our sensitive data on PC`s. I would like to know if someone here has any idea about those softwares? What would be better? We are running on Win XP Professional OS. [B]A reliable ******** support is also a must[/B]. We have seven computers and are sharing the location with another small company.

I`ll be glad to get some opinions :)