- last post: 01.01.0001 12:00 AM PDT
You won't need it. There is a specific program meant to run it, which is completely product key independent, given you have the maps, which are avaialbe for download, but its a huge download.
Also making custom gametypes will be a pain without another copy of Halo.... but all in all, it IS possible to run it without Halo installed on more then one computer
(Read the stickies, theres some guide for making a dedicated server I think)