Did this work for you? I am having problems. The sound isn't working in the RP but it was working for the CP. I have tried downloading and installing from that link as well. I get SBXF_PCDRV_WIN8_BETA_US_2_18_0015A.exe run it (tried admin/compatibility mode) but it just says "Setup is unable to detect a supported product on your system". I know for a fact I have the Sound Blaster x-fi XtremeGamer.
Any help would be most grateful
You have a real X-Fi card, not one of the re-labeled Audigy ones, so the drivers ought to work. They did for me.
I had the Windows 7 drivers released already installed. (I probably used the "troubleshooting" mode to install them.) I installed the Win8 beta drivers over those. Whether that made any difference, I don't know.