As far as you devices being shown, the HDMI one is likely the Audio device on your graphics card.
This is Ok to install if you have/use HDMI and should not affect the funton of the X-Fi.
It should show up when the driver
My X-Fi shows like the snip below in sound devices, so what you are decribing sounds to me at this point as normal.
When you disbaled the onboard, how did you do it? In device manager or in the bios?
Onboard should be disabled in the bios.
If you installed Creative Software form the CD, the only thing I would recommend installing are:
1) The Volume Panel
2) THX Console
They should be installed by setting the setup.exe as Compatability mode Vista SP1 and run as admin.
The Drive, Audio Console, and all other softweare you want should be downloaded from the official site. There are Windows 7 x64 versions.
I too have heard all the horror stories, but fortunatly have not had any issues with my X-Fi using the official drivers
/software. This is how I installed mine if it matters.