In my case Oblivion CTD'ed a lot with modifications, but the problem probably came from one of them, or a combination of them, or bad load orders, or bad coding from the modders, vanilla Oblivion is alright. In Fallout 3's case I've had a single CTD in my 70+ hours game, however it does freeze and hang the whole OS each two to three hours of play in each and every single sessions I've had so far, forcing me to hard-reset my system, each time, it never miss. I'm currently on a halt and waiting for a patch exactly because of that problem, and that problem only, or else I'd be playing it whenever I have spare time.