I have 2 gigs of 533ddr2, dual channel ram in my 9880.
There is zero stuttering in F.E.A.R. for me. My rezz is at 1024/768. Apart from the soft shadowing, I have everything else damn near maxxed out. I'm even using the high detail texture setting.
When I went from 1 gig to 2 gigs, I really noticed the difference with the high detail textures. No more virtual memory being used. It's all in da chips. Stuttering gone.
If you have less than 1.5 gigs, I'd recommend usuing the medium detail on the textures. It makes a BIG difference in the game performance but, a very small one in graphical detail.
Oh yeah, don't go by the perfomance test that Monolith provides in the menu. It's cool that they put it in there but, that thing had my settings WAAAAAY lower than what they are now. I bumped up damn near everything and it runs very smooth for the most part.