greyed out options
You can't have fullscene effects on at the same time as FSAA. Uncheck the FS effects and they won't be greyed out anymore.
You're not missing a whole lot without the AA, just stick with the effects. The game looks nicer. Now if I could only figure out how to get it in widescreen...
I just tried it again. With distance clipping on, AA and detailed shadows are still greyed out. I think distance clipping makes the game look like crap (it adds fog), and your gpu is better than mine, plus Gun's an old game so it's not exactly taxing on modern hardware.
So, clipping off and fullscreen effects off (basically bloom) if you want AA and better shadows. Its worth having both off.
This edit will also create new pages on Giant Bomb for:Beware, you are proposing to add brand new pages to the wiki along with your edits. Make sure this is what you intended. This will likely increase the time it takes for your changes to go live.