Let's see if we can't get your card working. The following steps should get your card working,
1. To rule out any compatibility issues, make sure that any drivers and software for the onboard audio is uninstalled. Also make sure that the onboard audio is disabled (can ignore this is it has been disabled from the start).
2. Download the driver package from here, SB X-Fi Series Support Pack 2.0 (05/15/2009) - Creative Labs
3. Uninstall anything Creative related through Programs and Features.
4. Extract the above file. It is a self-extracting file, so no need for any other program. Once it is extracted cancel the install.
5. Follow the steps shown here, Device Manager - Install Driver - Vista Forums
to manually install the driver. When you get to the step of locating the appropriate file you want to go to the following folder,
the file needed is called "wdma_emu.inf".
6. If #5 is successful in getting the driver installed, you should then be able to run the setup.exe from the main extracted folder to install the apps (or only the ones you want) from that driver package.