I would actually call dell about this, if you still have any free tech support available, and ask them what chipset they used for that video card, or if there's a generic driver available or a linux driver.
After poking around, it actually looks like it could be an intel810e chipset. But I am not too sure on that, it's kind of hard to search for PC specs on some else's computer. Anyway, over at Dell's website, I looked up the Optiplex GX260
, and I don't know if it's the same, but if it is, then according to that page, it's most likely the "Integrated Intel® Extreme Graphics with up to 48MB shared memory" And if so, then I would think that the page
where I read it was an intel810e graphics card, is correct.