Encryption for Notebooks

I am currently a IT Support Engineer for a small company. My boss is looking for an encryption product for our Windows 7 Notebooks. These notebooks will be on domain, so one of the trade off's is that we need it work with the user's credentials. You know something to similar to Mac OS X.

We've currently been looking at Enterprise but that as of right now is our last resort option. If you know of something or can point me in the right direction I would be very appreciative! Thanks.