The type of mounts can vary, usually either brass posts or spung metal clips.
These "stand off posts" hold the motherboard clear of the mounting plate.
Before you fit any of the posts in the case study the motherboard closely, you will see between 6 and 8 (usually)
mounting holes that have a bare solder ring on the upside.
The mounting posts must only be fitted to align with this type of hole (it is very important you use only these points to mount the board) as these points are dedicated earthing points and are meant to touch the case. BUT NO OTHER PARTS OF THE MOTHERBOARD ARE TO COME INTO CONTACT WITH THE CASE.
The motherboard is then screwed onto these posts (NO FIBRE WASHERS ARE REQUIRED)the screws make direct contact with the board, and the brass posts directly to the underside of the earthing mounting point holes.
You most definately do need a dedicated heatsink and fan to mount ontop of your XP1600+ processor (do not under any circumstances turn on the PC with this being properly fitted) use an AMD recommended heatsink/fan unit or seek guidence from your supplier.
Better still, take him the motherboard and allow him to fit the heatsink to the processor, it is very easy when you know how but in the hands of a novice the CPU can be easily chipped.
Recess on the underside of the heatsink goes over the Socket A writing on the processor socket.
Don't forget to peal off the protective tape on the heat transfer pad. (or apply heat transfer paste in the absence of a pad) Martin
Just trying to help, sometimes falling short, I am only human after all.