We use Utimaco software for Full Disk Encryption on all of our workstations. We haven't gotten to the point of encrypting servers yet. I believe they have demo copies of their SafeGuard Easy Software, if not let me know and I can get you a demo version.
I don't think the boot up takes any longer on our workstations but the initial install takes a couple of hours (as expected to encrypt the full drive).
Cheers.
