Halo 3 Heroic Map Pack is Free to download
The Heroic Map Pack is available for free from the Live Marketplace. To get this download sign into Xbox LIve and go to the Marketplace blade. From there select the Game Store and then select All Games. You’ll get back a big list of all the 360 games so instead of just scrolling down the list you can hold down the right trigger to page down until you get to HALO 3. After clicking on HALO 3 you will see towards the bottom the Heroic Map Pack , seclect that and confirm the download and you’ve got it.
The 487Mb file took about 35 minutes on my 3MB DSL to download.