Sorry to bump this, but no solution has been forthcoming and I'm pretty desperate for help.
I'm running a clean install of Oblivion, straight off the disc, and it still isn't working. I've tried disabling my second monitor and reinstalling, playing in compatability mode, all sorts of things. No dice. From what I can tell, others can run Oblivion on a 64bit Windows 7 PC, and my drivers are all up to date, so that shouldn't be the problem. Crashes everytime, though.
So is there really no one who has an idea of what is wrong? I can't be the first person to experience this problem.
Edit: Well, this is awkward. Almost as soon as I posted this I finally found a solution. Turned out to be a dual problem of Oblivion hating my second monitor, and a corrupter .ini file somehow finding it's way onto my new drive without me even knowing it.