Oblivion should be okay with a certain mod i found on the net.  I have a 1.6 GHZ laptop, integrated graphics card, 512mb RAM and using that mod i could run Oblivion on full graphics.  Yeah, honest!  It's called "Oldblivion" and is designed for older systems, so you could probably just use that. 

BUT

Resi 4?  I doubt it.