If you have Windows 8 installation disk, put it in, boot from CD, and install. Now delete all partitions and Make 1 for Windows. If the installer makes 2 partitions, click on the 2nd one (NOT on the System Reserved) and delete it. NOW click on the System Reserved 1 and expand it. U should see only 1 partition. Install W8 on it.
You can change name (System Reserved, if it annoys you, by right clicking on partition in Computer and rename). If you want extra partitions for data (which is good, because if you have 1 partition and ur W8 fails, then you lose all data), click manage on the computer and then shrink C:/ . I'd personally leave 75GB for C and the rest would go to D.