<<< Is replacement simple, do i need to find out if it is master or slave and if so how? >>>
The drive is connected by a Power cable, IDE ribbon cable and, possibly, an Audio cable. Unplug these, remove the (four?) screws that hold the drive in place and slide it out through the front of the case.
At the back of the drive, there are "jumpers", pins that can be bridged to set whether the drive is set as Master (MA), Slave (SL) or Cable Select (CS). Use the same option as your current drive, although the pins to bridge might be laid out differently on a new drive. They will be clearly marked though.