Follow this guide, it helps A LOT
http://www.tweakguides.com/Oblivion_1.html
http://www.tweakguides.com/Oblivion_1.html
Ah its amazing! Depends what games you call light, but the 9600gt in it can handle left 4 dead on mostly high (a couple of mediums thrown in) at a very good frame rate
Just have to be aware it gets hot when gaming in windows (ie i have a book or pillow between it and my knees if i dont have a desk)
Other games it can handle well are half life 2 (well all source games), civ4 and age of empires 3. My theory is oblivion should be fine too