The iso is 486.3 MB (509,935,616 bytes). You burn it to DVD-R because that's the most universally readable disc format across all of the Xbox DVD drives. It will work from a CD, but only if your Xbox DVD drive will read burned CDs properly - and many don't.
Will a DVD+R work? I finally got the download and burned image on a DVD+R. I can't try it yet because I am waiting for my USB card reader to come in the mail....and other things.