HDD is the hard disk device or hard drive device where the operational system Windows XP and all datas , including your espics etc.. are storaged.If it works the red light on your computer flashes.
for other datas you can use the way....click on the icon My computer on the desktop with right mouse button., then choose properties..If you don't have the icon there go to Start menu ( right bottom corner of your screen), click it and find the Computer option.Then click it like depicted above and get in properties.
Also use Start menu , then choose Run and tape "dxdiag"and click run button.