HOW DO I BURN MDF & MDS FILES USING NERO??

im trying to create copies of my games to play in the pc, but have had no luck so far. i created an image of quake4 using alcohol 52%(which created an mdf & an mds file), but dont know how to burn them to disk with nero, so that it will play in my computer. i want to do this so my originals stay scratch free, & if i want to play a game, i can just put in the copy. i tried copying & pasting the files from the original disk to a new folder on the desktop, using FOLDER2ISO i then turned them into an iso file & tried burning it to disk, but it didnt work. does anyone know how i can copy pc games to dvdr? i also, have dvdclone2 but that didnt read the disk. & magiciso, i havent tried, but ive tried everything else & would appreciate some help, advice, or suggestions. thanks