Why might you use the Extend Disk Partition option?
Typically you can only have 4 primary partitions per hard drive if you are using the MBR partition layout scheme. If you need more partitions than the maximum allowed (4), then there is a way to get many more partitions with only one hard drive.By creating an extended partition you can have as many logical partitions as you need within that extended partition, thus you can have more than only four partitions. You can have 3 primary partitions and one extended partition (for a total of 4), and inside the extended partition you can have as many logical partitions as you need.The one thing to keep in mind is that any type of Windows Operating System needs to be installed in a primary partition, otherwise you cannot boot into it. Windows XP in particular, needs to be installed in the first primary partition. For everything else, you can create as many logical partitions as you want inside the extended partition.