From a University of Princeton study? Not very.

We use cold reboots to mount attacks on popular disk encryption systems — BitLocker, FileVault, dm-crypt, and TrueCrypt — using no special devices or materials. We experimentally characterize the extent and predictability of memory remanence and report that remanence times can be increased dramatically with simple techniques.
http://citp.princeton.edu/memory/

Full story sent to me is below.
http://www.networkworld.com/news/200...n-cracked.html

Just food for thought for those of us regulated by HIPPA, FERPA, or other government privacy laws that may require the use of a Full Disk Encryption solution.


Ciao