http://xrl.us/begdkc , abgx360 (use that if your planning on using those backup's on xbox live) ... using that is not required but if your using xbox live, then using that is pretty much required if you want to minimize your chances of being banned on xbox live using backup's.
also i would make sure your console is using the newest iXtreme firmware which is v1.5 (unless you got a Hitachi then it's still v1.4)
also as said above use on Verbatim DVD+R DL (made in singapore) if possible.... i burn @ 4x since disc quality scans show you get better burns then burning at the standard 2.4x.... so my advice is burn @ 4x unless you have issues then try 2.4x.
if you got your own games... depending on what drive is in your XBox360 you may or may not need to buy a Kreon drive on ebay cause with the Kreon drive you can read the original XBox360 games so that you can copy the game data to the PC which will make a .dvd file and .iso file with a program called XBC (XBox Backup Creator , http://xrl.us/begdkr ) then use that abgx360 program to patch the .iso file as needed (it comes with a .PDF file that tells you what to do) then burn it with ImgBurn ( MODE > WRITE ... then load .dvd file and burn @ 4x ) then your good to go.
if you got a Samsung drive in your xbox360 then you can use that to read the original discs but it's not really practical since you gotta open up the xbox360 and flash a different firmware (xtrm0800.bin) to it temporarily so that the Samsung MS25/MS28 drive can be detected it windows so that it works with XBC application and then after that's done (dont making your backups) then you have to flash it back to iXtreme v1.5 firmware so that your xbox360 will work with backups again.... so as you can see even though this will work and is free (assuming you got a Samsung drive in your xbox360) it's not really practical... which is why the Kreon drive on ebay (about 50 bucks) is a much better option.