Sapphire 5870 Problems Installing Drivers

Well I do not really know where to start. I've bought myself a new computer and I'm trying to set it up and completing updating stuff.

And Everything goes smooth until the installation of my new Sapphire Radeon Hd 5870 Graphic card.

I'm not any expert in this field and could really need some help, directions or what to look after to make it work.

I'm able to install all except the actual driver. The drivers I'm trying to install is latest from Ati's homepage.

The error message i get is following:

"Driver install: user must be a member of the administrators group"

Error During installation of newest Drivers

I've tried right clicking and Run as Administrator but nothing changed and I still got the same "result" or problem after that.

I've checked in my Administrative Tools -> Computer Management -> Local Users and Groups -> Users

And there I've checked that my User is a member of Administrators.

I've tried starting up a game (Aion to be correct) and got this error:
Error Message Starting up Aion

I've tried to install new drivers by selecting the location off the driver but then windows gave me a message that said following:

"Windows has determined the driver software for your device is up to date"

Picture shows Advanced settings in Screen Resolution
Picture off Advanced Screen Res. Settings

On my Motherboard, Asus Rampage II Extreme, It said that if you were running a single GPU card it should stand at the top Pci-e slot, so it's mounted after the manual.

I don't know if that makes me unable to try the 2nd or 3rd Pci-e slot to test the actual slot or not?