Now I think I understand what you mean by caddy, this is probably a mounting rack/kit for the inside of the computer case.
Many manufacturer's portray the drives this way. This is not an actual photograph of the drive you're going to get, but you should be careful with who you buy from. I'd suggest that you do it from an authorized reseller or directly from the manufacturer's website.
As for the motherboard, I was asking, because I wanted to take a look if it has SATA ports, because you mentioned an IDE cable and i wanted to be sure that you don't get a drive which you wouldn't be able to connect to the motherboard.
To find out what's motherboard you have click start and just type in
dxdiag and press "enter". This way you'll open the DirectX Diagnostic Tool and in the first tab - system (which will be selected by default) you'll see 2 lines: System Manufacturer and System Model, those 2 show the manufacturer of the mother board and its model respectively although if the computer is OEM (bought from a specific brand, there would probably be shown the model and name of the computer instead of the motherboard).