I'm playing Oblivion with a 1680x1050 (widescreen) resolution, 2x anti-aliasing, medium sized textures, bloom and distant land features. I don't have any mod for graphics, the mods I have only add game content.

It usually runs with 60 fps but then on some situations it has breaks (like casting spell, when I'm in a city, when I'm in a building with many NPCs), and many times the fps can go to 30 or something like that.

CPU: Intel® Core™2 Quad CPU Q6600 @ 2.40GHz
RAM: 4.5 GB
Video card: GeForce 9800 GTX
Sound Card: Realtek High Definition Audio
DirectX: DirectX 11.0
OS: Microsoft Windows 7 Enterprise Edition Service Pack 1 (build 7601), 32-bit

I have some suspicions the video card might have problems...