Most often when people dual boot it is between a Windows OS and a Linux OS.
The pros are that if you like to run Linux but also like gaming you can use Windows for gaming and Linux for everything else.Also if if one OS corrupts itself(most likely Windows) you won't lose access to your data.Cons are that using another OS on a smaller hard drive can take up a lot of the drive's free space.
Since you've got Windows already if you were to install any major Linux distribution it would partition and format the drive automatically.
But I don't have a lot of experience manually partitioning hard drives so I'll leave that to someone else more knowledgeable in that field.
Hope this helps.