if your using XBox Live it's strongly recommended you use the newest firmware (which is v1.5 for Samsung/BenQ/Lite-On) AND use the application called abgx360 to make sure your .ISO is patched properly to minimize chances of being banned on xbox live.
http://xrl.us/bebjoi (it comes with a .pdf that tell's you what to do... and if you dont use or care about xbox live then this program (abgx360) is not necessary to use)
also, if you want to make your own backup's it's a good idea to buy a Kreon drive (u can get em on ebay for around 50 bucks) BUT if you got a Samsung in your XBox360 you can use that to make backup's of your original discs but it requires re-flashing it to xtrm0800.bin firmware which allows it to be read in windows with the XBC (XBox Back Creator) application.... but like i say, using the Samsung drive in the XBox360 itself aint really practical since everytime you want to backup a game you would have to open the system up and re-flash it etc etc.
p.s. i personally burn @ 4x as i get better burns that way vs 2.4x according to Kprobe.
p.s. what ramaa said above aint necessary to do (about the "setting>write>Layerbreak>user specified "1913760" important !!!!" ) cause when you load the .dvd file it contains all that info for you already... it's only if you dont have a .dvd file that what he said would be required... although it wont hurt anything if you do what he said.