I have made about 10 copies that did't work keep getting the dirtydisc error message screen .I have made a ISO with about 4 different programs( SIMPLEX, XISO, GNUGDFIMAGE, QUIX, and some others) and also tried DVD Decripter and Nero 6 to burn the iso's nothing has worked so if anyone could please help.
What kind of media did you use? Did you use media that was compatible with your xbox? It doesn't matter how many times you made a disc, if your xbox doesn't like it, it will reject it. I have to believe this is the reason why you keep getting the "dirty disc error"
But now that I think about it, why are you getting the dirty disc error anyway? If you have a modded xbox, you should also have a dashboard (besides the standard MS dashboard). So why would you be getting that message if you have a dashboard?
If you don't have a modded xbox, then you might as well quit trying.
Halo 2 is too big to fit a standard 4.7 GB. And you probably didn't cut out the Xbox Live files to make it fit on the DVD.
Did you cut out the Xbox live files (downloader.xbe, update.xbe, dashupdate.xbe) before making it a ISO and burning it? Because if you didn't, then that's the problem.