T400 w/Switchable graphics - trouble upgrading Intel video

[Dead1nside]

Hi, I've got a T400 with switchable graphics but I'm having problems at the moment trying to upgrade the Intel video driver. I've downloaded it from the website and unpacked it, however when I launch the setup.exe I get the following error:

Error: The computer does not meet the minimum requirements for installing the software. Setup will exit.

I'd really like to upgrade the driver to see how capable the 4500 is. Thank-you in advance.

Edit: When I open up the Intel display adaptor in Device Manager it says that the vendor is ATI and that the version is 8.520.4.5000.