WE External Drive 5009A

I have an WD external harddrive connected to a Windows 7 PC. The model number appears to be 5009A. The WD part number is WD5000H1C8-00. It is connected to the PC via USB. Can anyone point me to some documentation about this drive? What is the capacity? How do you tell if it is turned on?

Not 100% sure if this is your model

http://support.wdc.com/product.aspx?ID=110&lang=en