I want to create a dual-boot such that the content of each OS is separated from the other using encryption. The main point point would be to to test out potentially harmful software on one OS, and still be able to rely on the integrity of the other OS. 

User A uses OS A and User B uses OS B. Lets assume:

* both OSes are Windows 7.
* two different partitions, one for each copy of Windows.
* one physical storage unit available such as on a laptop
* users of each OS both want to brute force (not vs each others) using attached hardware or use third-party software involving card readers
* it is acceptable for each user to be able to destroy each-others Windows by erasing or over-writing a partition.

However neither user should be able to access or modify plaintext data from the other user's partition. 

In the past I have arranged this with TrueCrypt and Hidden OS. I am looking for other ideas that are easy to implement and, more important, don't take a lot of time. I would prefer an arrangement that included only open source software.

Is this possible? If so, how?