You may have to go the old school route and manually add it. In the control panel click on Add New Hardware, click Next and the wizard will search for the new hardware. When it doesn't find it, it will pop up a screen asking if you've already installed the hardware or not (make sure the card is already installed). Select the option that says the hardware is installed. You'll then get an option of devices and scroll down until you find the devices for the soundcard. Select that and it should then bring up a manufacturer's list. Scroll down until you find Creative and then click on "Have Disk" (make sure the CD with the drivers are is in the CD drive) and then browse the CD until you find the correct .inf file (it will usually be in the Drivers folder in the CD) and select the appropriate .inf file. You should now have the option in the Model (product list) for the X-FI sound card. Select it, follow the instructions and hopefully it will work.
Also, make sure that your onboard sound is completely disabled in your BIOS and in the Device Manager (just need to select the Disable this... in the properties). Also, check to make sure that you don't have any other devices using the same IRQ to avoid any IRQ conflicts.
anyway, that's what I had to do when I slapped in my X-FI into my new system.
ack-ack
