Really?
I play it on a 7 year old computer and it runs fine.Of course it will run perfect once I get my new computer in a few months.Right now I don't have any issues playing except for a tiny bit of lag once in a while and it never crashes.I also play it vanilla though too.
I'm not sure what "fine" means. One person might feel that lowest settings, occasional lag, and no mods was "fine," and another might call it "not very well."
The age of the computer isn't the issue. The Sempron CPU and the old 6200 graphics card are both at the bottom of the heap. That system meets the minimum requirements, but that's about it. Oblivion may run on low settings. I wouldn't plan on mods.
Edit: I'm putting in a request that this thread be moved to the Hardware & Software forum, so the more tech-oriented people will see it.