Do I need to buy any other items?

Solution
It should come with the cables. The motherboard should come with a couple of sata cables to connect the hard drive, the psu contains the power cables needed for the drive(s) and motherboard, the case includes the cables needed for the front ports and power button. You mentioned you have the os, if it's a disc you'll need an optical drive (cd/dvd rom).
It should come with the cables. The motherboard should come with a couple of sata cables to connect the hard drive, the psu contains the power cables needed for the drive(s) and motherboard, the case includes the cables needed for the front ports and power button. You mentioned you have the os, if it's a disc you'll need an optical drive (cd/dvd rom).
 
Solution