Re: Booting from DVD...
I had that problem once, it kept seeing my X-Fi as a Intel HD Audio device. I forgot how I fixed it. I think I removed the device and reloaded the Creative drivers and kept rebooting. I might have manually tried to install the driver and pointed the install folder to the Creative drivers INF.
On my EVGA x58 MB, my USB mouse and keyboard work before the OS. There's an option for legacy support or something.