Remember, that
Oblivion really has no maximum settings. You can, of course, push the settings available in the in-game settings dialogue to their maximum, but through the .INI file, they can go even higher, and there are some options not even normally available. (such as making water reflect rocks, trees, creatures, the player, etc.) Plus you can also add texture-replacement mods to go from "large" to "super-sized."
With enough pushing, you can bring even an 8800GTX SLi setup to average 5fps. Ouch.
However, for the time being, I'm not certain if you really need a new card. While you probably might not be able to quite reach what you want with the current setup, you're not really ALL that far from it. However, if you want extra smoothness, I think that something like at least the Radeon X1950pro, or possibly the Radeon X1950XT. But up at that point, nVidia's GeForce 8 series looms, and unlike the Geforce 7 or 6, it's not a wimp with shaders,
Oblivion's main killer. While the Radeon X1k cards tend to spank the GeForce 7 cards in
Oblivion, the GeForce 8 cards muscle their way around rather well.
Lastly, if you plan on using texture-replacement packs like those made by Qarl, you'll want more than 256MB of RAM. At the very least, you'd want 512MB, possibly more; even at a resolution like what you list, it's possible to over-fill even the 768MB GeForce 8800GTX.
Hi Guys . Hey Pauldh how about a X1900XTX ??can i play oblivion like you said??i mean can i play the Oblivion in 1024x768+4xAA/16XHQAF W/O Self Shadows with 20~30FPS??
The X1900XTX is still a substantial step away from the X1950XTX; the core is effectively the same, (the "+" on the "R580+" merely indicates that its VRAM controllers are modified to support GDDR4 as well as GDDR3) but the clock speeds for the RAM are different; 2000MHz compared to 1550MHz. The core's power on its own is the same, though.