The first partition (C: if it's the first hard or only hard drive) is the Primary partition. This must then be made active if it is to be bootable.
The remainder of the drive space, (assuming that primary partition is smaller than total drive capacity), is then partitioned as the 'extended partition'. This does not have a drive letter assigned to it. Logical partitions are then created inside of the extended partition.
Yes it is all coming back to me now
That is one draw back to using Partition Magic, after a while you forget the basics. I used to know this stuff when I used fdisk.