Upgraded to 9800GT. Now sound doesn't work.

Problem description: I upgraded from a 7800GTX to a 9800GT today, and now my sound doesn't work. I use onboard sound, and it was fine with the 7800GTX. However, once I uninstalled the video drivers for the 7800GTX and installed the drivers for the 9800GT, my sound stopped working. Four things are listed with a yellow question mark in my Device Manager now that I've never seen before:
Multimedia Audio Controller
Other PCI Bridge Device
PCI Memory Controller
SM Bus Controller

Also, when I go to "Sounds and Audio Devices," it says "No Audio Device" at the top.
Edit: another thing I should add is that these problems occur even when I have no video driver installed.

Attempted fixes: I reinstalled the video drivers, to no avail. Checked the BIOS to see if my onboard was disabled--it's set to "Auto" with the only other option being "Disabled." Googled a shitload and now I have a headache.

--

Operating system: Windows XP Pro

System specs:
BFG 9800GTX
ASUS A8N SLI-Deluxe motherboard
AMD 4400+ Dual Core CPU
Onboard sound
(I think that's everything that would actually matter when dealing with this problem)

I have Googled and read the FAQ: Yes

NOTE: I am no good with computers so if there's a driver I need to download please try to give me direct links

 

Reinstall all your drivers from the A8N CD, all of them, then install the 9800GT drivers and reboot. I have an A8N also and I seem to recall that's what I did.

 

I dunno where the CD is . Any links?

 

OK, I'm bored tonight. http://support.asus.com/download/download.aspx?SLanguage=en-us third one down, it's only the audio driver but it should work. Save it first and then run it. I'm assuming you're using XP 32bit.

 

Thanks for the help I have to choose some options to see what you're talking about. Just clicking that link won't bring me to what you saw. What do I click?
I know I put Motherboard, then Socket 939, then A8n SLI Deluxe, but what do I do once I hit search?

 

Click on audio, then third one down for your setup. Hmm, I thought I gave you the exact page but apparently not, guess ASUS doesn't like direct links.

 

I only see this:

Realtek ALC850 AC'97 Driver V5.10.0.5900 WHQL for Windows 2000/XP/2003 & 64bit XP/2003.

Is that the correct one? How do I install it?

 

Hmm, driver looks OK. download it somewhere easy to remember, say your desktop and then double-click the icon and answer the prompts. The download will take quite a while as ASUS is a darn slow site, especially tonight!