I just downloaded and installed the drivers on the top of that page in the link, and the sound still does not work. I went into the SB X-Fi Volume Panel (down by the date and time), and went into the THX Setup Console section, then went to 'Diagnose'. It did some tests, and here are the results:
Creative Diagnostics Test Log
Detected device:
SB X-Fi [E800]
Tested device:SB X-Fi [E800]
05/17/2008 09:05:58AM Drivers Tests Pass
05/17/2008 09

02AM Windows Multimedia Tests Pass
05/17/2008 09

03AM DirectSound Tests Pass
So I still don't know what the problem is :P