Vista - Help understanding Vista Home Basic and Hard Drive reccognition?

I have win Vista Home basic installed on the same computer twice. One is
running on a scsi drive with two partitions and the other is running on an
sata drive. Both op systems are bootable using vista boot pro. Problem I am
having is the op system installed on the scsi drive does not reccognize the
sata drive which has two partition on it. One being the op system and the
other for backup and both are primary partitions. When I boot from sata
drive i can see all partitions on both drives. Why is this so if anyone has
any thoughts on this I would be delighted to be able to access all
partitions on both drives frome either or? Thanks for any input that would
help me resolve this conflict or whatever you can call it.(problem)