Enabling BitLocker Drive Encryption with hidden system partition

Hi,

I have been using/testing vista ultimate since beta 1 and was able to
install 2 partitions with a 2G system partition (active w/o drive letter
assigned) and the rest of the hdd as boot partition (windows installation,
otherwise known as c: drive) during the beta build.

With the release version, I was not able to re-create the same setup. Tried
installing twice so far.
Reason is to prevent users from storing files in that partition (since it is
visible) thus preventing drive encryption from working.
Is there a way to install w/o assigning drive letter to the system
partition? The other alternative is to assign another drive letter in the
higher order, like s: drive (if there is no other choice but the interesting
thing is I was able to install with a hidden system partition during beta
built)

Regards,

Lawrence N