Is it normal for the computer power light to blink?
Yes, if the computer is sleep or standby mode it is normal for the power light (LED) to flash or blink. This lets you know the computer is still on, it's just in a power saving mode. If your computer is in this mode press any key on the keyboard or press a button on a mouse button to get out of the power savings mode.
Hard drive light
Many computers also have a hard drive indicator that flash each time the computer hard drive has data read from or written to the drive. This light will flash often or stay on solid for a few seconds frequently as you work on the computer. This too is completely normal.