A. Someone gave you some bad information. It would be wonderful if partitioning a hard disk could double its capacity, but no, that's not true. Partitioning breaks a large hard drive into what appears to your system to be multiple, smaller drives. You can gain some hard drive space by partitioning, though. As I've written in this space before, in the original File Allocation Table system used with MS-DOS and early Windows 95, smaller drives require less overhead per file, known as clusters.
Bigger drives require bigger clusters, so more space is wasted per file.
You don't necessarily need to partition, however, if you have the right operating system. The amount of reclaimed space varies, depending on the size and number of files on your hard drive. Whether your system will support an extra-large drive depends on the operating system and the system's BIOS, which manages a PC's most basic systems. Check with the manufacturer of your computer to see what it will support. You probably can use special software that would come with such a disk that would let an older PC see all of the large drive's capacity.