First off, why would you put it on the 32GB partition? That means if you want to install lots of programs, games, etc you will need to manually change the installation directory from the C: drive to the second partition, and if you want to store lots of media/files you will have to redirect your "Users" folder to the secondary hard drive.
Personally I would just combine both partitions by deleting both of them from the Vista installation (if there's nothing needed).
As for the reason why you don't see it, it's because it's just unallocated space. Go into the disk management utility (start > control panel > administrative tools > computer management > disk management). Then from there you should see the 600GB of unallocated space, simply right click on it and click "format".