We currently use Checkpoint's Pointsec product. I have mixed feelings about Pointsec. I think it is all around a great product, but a little difficult to manage. It works on quite a few different OS platforms. Support isn't the best. However, you can implement their full security suite to provide OS control and removable drive encryption as well as Blackberry encryption I believe.

Another company I looked into that did not meet our two factor pre-boot requirements, is Credant (http://www.credant.com/). I was really impressed with them, and wished we could have taken a better look into thier product(s).

This is just my experience with a few products, but I think your decision will vary according to what your security policy, and environment looks like. Remeber that free is good, but when your encrypting someones data, it sure pays to have support when something goes wrong.