System virtualization and FDE

When I used PowerShadow I remember it always asked at boot time if I want a partial or full system virtualization.

I am planning to implement full disk encryption. When the preboot authentication asks me for the passphrase how can I choose if I want to boot in virtualized or non-virtualized fully encrypted OS?

This may sound silly to somebody, but it confuses me a bit and I want to make sure I do it properly.

Anything else to consider when combining full disk encryption and virtualization?

 

I can tell you that Truecrypt and Returnil get along fine. If you want the virtualization "on" you just reboot, put in TruecCrypt password and it boots into a Returnil "on" environment. Same for turning it off. Nothing is different except that the system drive is encrypted and you must put in the password on reboot, otherwise you use Returnil as normal.