To extract the ISO:
1) Download WinRAR
2) Open the first file (should end in "part01.rar" or something similar) using WinRAR, then extract the ISO to wherever you want (it will automatically extract it from all of the parts, be patient and wait till it's all done)
Now, when I say "using WinRAR ... extract the ISO," when you open "........part01.rar" (or whatever it's named, but the first part) in WinRAR, you'll have the option to "Extract To..." - that is what you want. Save the ISO to wherever you want, desktop, documents, whatever. Then, using whatever program you have at your disposal, burn the ISO to a Dual-Layered DVD.