Well, N450 and a GMA 3150 isn't much horsepower. You'll find a vid on youtube with someone playing Oblivion on an atom (I think) with your specs. I think its prefs.ini was modified for almost no distance, no detail and fog like a london rain day, but it chugged along at a very choppy fps. So it worked.
I have a 1.5 yr old netbook - which i have tested gaming on. Wasn't even an expensive one.. Gateway LT22 w/2gb (AMD K125 & ATI Radeon HD4225 ) and it plays low detail Oblivion at 27-34 fps , fallout3 at about 20-24 fps. New Vegas at 14-18 or so. Each game seems to be more CPU/GPU intensive. Just picked low detail for those. I think I had to modify the ini file to fit the awkward 1024x600 screen tho. I'm installing Skyrim for a laugh, but I would be surprised if it plays it at all on low even.. its a much more resource hungry game than the others.