im glad you guys are having better luck with this ini file than I am with other games nobody else seems to be researching. I found kick butt graphics options relevant to their PC counterparts for Unreal Championship's UC.ini in directory "Y" and when you back your version of Rainbowsix up so you can play on Hard Drive you'll find a similar RainbowSix3Xbox.ini
Now, my luck in the past of ini editing on Xbox has turned up nothing but bad. I either make it so my profiles don't load (when editing user.ini files) or can't get them to reflect changes. Such is the case with UC and RainbowSix. Anyone know how to sign the ini files so that the games think they are the original default.ini? I've seen people do it with Unreal Championship's User.ini files and I can't figure out how they did. If I could figure this method that, I'm sure tons of people know, I can have both Unreal and RainbowSix, Splinter Cell 1 and 2, Theif and Deus Ex (all unreal based engines) at a nice level of graphics splendor. RainbowSix doesn't even have the command line UseXboxFSAA=true and Cachesize megs is only set at 1mb where in Unreal its 8mb. Non of these games use the full 64mb of the system. Only 32 from what I read in OXM about Unreal Championship when it first came out.
If I can get the ini files signed correctly, the games will look tons smoother.
So start working on any of the above mentioned guys.