Well I think you need to look at it in context when you put it like that. Though I will just add that the 360 version has had a new patch that fixes a lot of those issues
To play Olivion maxed out with fluid framerates I'm thinking your PC cost more than the £200-£280 your Xbox 360 cost you?
I mean can you really compare £1,000's of pounds worth of cutting edge PC performace with a couple of hundred pounds worth of 18 month old console? I play Oblvion in HD on my 360 (only 720p though) and think it plays very well and it looks stunning
What res were you playing Oblivion on your PC btw?