I had a similar problem with the Asus ACPI driver for vista. I was able to unzip the file and go into the extracted files and copy the sys file into my c:windowssystem32 folder. After that the driver installed correctly. You may want to give that a try. You could also try to run the driver installer as an administrator by right clicking on the file, select properties and go into the compatibility tab and select run as administrator. You can also just right click on the file and select run as administrator.
I have trying to install Canon PowerShot S5 IS and I received the following error. In windows server 2003 I enabled service Windows Image Acquisition and it worked. I don’t know how to enable this in Windows Server 2008. Any idea?