some interesting info on comparison between the two platform supported by the game, the 360 version seems very very good, this is a good thing, as I don't have to upgrade my pc until (maybe) vista will arrive, with dx10 games :
"Personally, I felt that the Xbox 360 was the better version of the two. While the PC version has the ability for mods later, the Xbox 360 framerate was much smoother than the PC version. The PC's we used had a top of the line video card, so if these machines had issues running the game smoothly, you'll have to turn off some features to get a smooth framerate on systems with older video cards. While you might be able to run Oblivion on older video cards, I speculate that this could be like saying that you can run Strike Commander on a 386. It runs, but you have to turn off a lot of the special effects, and it won’t look like the pictures on the box."
"While some pop-in was noticable on both versions, it was more pronounced on the PC version."
"I went to the PC version of Oblivion. These machines were built with a Pentium 4 3.4 GHz, 2 GB RAM, and an ATI X1800 (possibly 1900, still confirming) video card. These machines were obviously very powerful. The monitors were Samsung widescreen LCD monitors. These were used for both the PC and Xbox 360 versions."
"The controls on the Xbox 360 just seemed more streamlined and smooth compared to the PC version. For instance, I never had any issues casting a spell on the Xbox 360 version. Unfortunately, trying to hit the C button on the PC seemed clumsy. Hitting the space bar to activate an object was counter-intuitive to using the left mouse button. The control was more natural on the Xbox 360 controller. I’m certain that getting used to the control on the PC shouldn’t be that great of an issue though, especially for fans of PC shooters. "
http://www.gamingtrend.com/Articles/articles.php?artID=132&pg=7
"Personally, I felt that the Xbox 360 was the better version of the two. While the PC version has the ability for mods later, the Xbox 360 framerate was much smoother than the PC version. The PC's we used had a top of the line video card, so if these machines had issues running the game smoothly, you'll have to turn off some features to get a smooth framerate on systems with older video cards. While you might be able to run Oblivion on older video cards, I speculate that this could be like saying that you can run Strike Commander on a 386. It runs, but you have to turn off a lot of the special effects, and it won’t look like the pictures on the box."
"While some pop-in was noticable on both versions, it was more pronounced on the PC version."
"I went to the PC version of Oblivion. These machines were built with a Pentium 4 3.4 GHz, 2 GB RAM, and an ATI X1800 (possibly 1900, still confirming) video card. These machines were obviously very powerful. The monitors were Samsung widescreen LCD monitors. These were used for both the PC and Xbox 360 versions."
"The controls on the Xbox 360 just seemed more streamlined and smooth compared to the PC version. For instance, I never had any issues casting a spell on the Xbox 360 version. Unfortunately, trying to hit the C button on the PC seemed clumsy. Hitting the space bar to activate an object was counter-intuitive to using the left mouse button. The control was more natural on the Xbox 360 controller. I’m certain that getting used to the control on the PC shouldn’t be that great of an issue though, especially for fans of PC shooters. "
http://www.gamingtrend.com/Articles/articles.php?artID=132&pg=7