Making use of both HDR and Antialiasing has always been tricky, previously in Oblivion only the Xbox 360 version could use both together. A few days ago ATI released a new graphics driver to make this possible on their latest range of PC graphics cards. Well today Hexus have posted their interview with Chuck from ATI discussing how they made this possible.

HEXUS: Bethesda said it'd take significant reengineering of the PC version that'd delay the game by months at best, hence why it couldn't be supported. So, have you invented time travel or what?
Chuck @ ATI In a way. When I first read that Oblivion wouldn't initially support HDR+AA, I was shocked and disappointed. Like everyone else, I was really looking forward to the stunning graphics in Oblivion and I wanted to turn on all the bells and whistles and see what it could do on the X1900. I knew that I could actually do something to get HDR+AA working for end users right away, so I went to work on a driver patch. I'll give you more details later.