Dual-boot with pre-boot authentication

"HOWTO: Set up Full Disk Encryption in a Dual Boot System.
(Using Truecrypt, Ubuntu+Windows)

TrueCrypt leaves behind a string in its boot loader that identifies it as a TrueCrypt boot loader. You can change this with some fiddling:
Modify Truecrypt encryption boot loader strings.

Note that even with full disk encryption someone can still access the data if they have physical access to the PC within a few minutes of it being powered off:
Cold boot attacks on encrypted partitions.
(Freeze ram, remove from pc, read key!)"

I've heard many good things about TrueCrypt, especially in the context of what you are looking for. I know that it offers options for full-disk encryption and password authentication and am almost positive that such features will work on a dual-booting system as well.

"Whilst Windows and Linux both have their own encryption technologies, I do not think there are any pre boot solutions that work on both.

Your best bet would be to use either a software based solution such as Truecrypt* or look at your usage habits and virtualise one in another... For example, if you do not do anything intensive in Linux, I would virtualise it so that you can use Windows as your primary OS and then use Bitlocker.

(*) I realise that this is not what you want, but there isn't really many encryption solutions that are cross platform, let alone pre boot.

EDIT -

Just read the documentation, and it looks like Truecrypt does/can do pre boot authentication... but I have never used this feature and cannot really give any advise other than to say Truecrypt is a good product!"

"Regarding the boot password, you may use a boot manager to handle the dual booting, one that supports passwords. The encryption can be done per operating system using available tools.

Some such programs are:

BootIt NG ($34.95)
This is the only one of the list with which I have personal experience and can testify that it's indeed maybe the best of its kind.

enter a password/keyword that will be
required to boot this item (operating system)

GAG (freeware)

Allows a password to be put on each
operating system, denying access to
non-authorized people.

PLoP Boot Manager (freeware)

Password protection for the computer
and the boot manager setup"