I'm running just a single card when I should have two. One went kaput so I'm waiting for it's replacement from newegg. As soon as I get the second 6950 I should be good to go again.
I feel bad saying this, but... if I recall correctly, two (or more) cards will at best do very little for Oblivion -
if anything - and at worst, might even reduce FPS. I hope it is the former, of course, and I suspect it is. But even so, I am
fairly sure that Oblivion is
very badly optimised (if at all) for Crossfire. Or SLI, most likely, for that matter.
Hopefully, I do
not recall correcfly, in that instance...
What are the main Beautifying Mods that people use?
First and most of all, http://tesnexus.com/downloads/file.php?id=30054, and http://tesnexus.com/downloads/file.php?id=37825 to go with it. All other graphical mods fade into the background, relatively speaking, in terms of how much impact they will have..
And, while I cannot remember all the many,
many mods I use, http://www.gamesas.com/index.php?/topic/1213147-oblivion-the-beautiful/ might prove to be rather useful for you, along with whoever else happens to be interested.
I do thoroughly recommend just about anything by
InsanitySorrow, or
AmpolX (if you can find the latter, that is). In addition,
All Natural is a must, along with
Cava Obscura. Oh, and most definitely
DarNified UI, or
DarkUId DarN if you prefer - playing Oblivion is maddening without one of these, or a similar UI mod.
But anyway, I imagine that the thread I linked to will be more helpful than any list of mods I could name here and now.
Best of luck with it all. Make sure you use http://tesnexus.com/downloads/file.php?id=22368, of course, and if you need some help with that - most people will - there is an excellent tutorial right http://tesnexus.com/downloads/file.php?id=35230. And lastly, bookmark http://tescosi.com/wiki/Main_Page and read as much of it as might apply to you and your modding. A (very) few things might be slightly out of date there, but for the most part, it is still entirely relevant.
Have fun! ( ... and, if you feel like it, post some screenies over at the Oblivion Mods foruim, in the Modded Oblivion Screenshots thread, which is generally to be found within the first two or three pages ... )