When you delete a Partition it is converted to Unallocated Space. But it is NOT added to the space already allocated to another Partition. So do not expect your C: drive to suddenly find more space. In fact, using just Windows' tools, there is no way to expand the C: boot Partition to add on some Unallocated Space. You CAN do this, however, with third-party software like Partition Magic, as long as the Unallocated Space comes right after the existing Partition on the disk.