Post about such things here:
Thread LinkI think that you simply don't have a good enough computer to run Oblivion. I've read many reviews of Oblivion lately about system requirements and such, and I come across over and over again is how you can have recommended requirements for Oblivion but still won't be able to run the game. But in this case I really think you have to set down the graphics pretty low... About that GW also crashes, well you should try to delete all crap from you're harddrive and close all other programs then the game itself - Don't know about the system requirements for GW, but this is all I can come up with...