Audio Codec Help

First off, a little info on this ancient PC:

Motherboard: ATI Ambermine M
CPU:AMD Athlon 64 3500+

Chipset
-------------------------------------------------------------------------Northbridge ATI Xpress 200 (RS480) rev. 10
Southbridge ATI SB400 rev. 00

Audio chip: Realtek ALC658 (Yes, I looked at the board)
PCI\VEN_1002&DEV_4370&SUBSYS_2A27103C&REV_02\3&61AAA01&0&A5


OS: I just installed Windows XP x64 (I wanted low memory but remain 64bit on a dated machine)


So the problem is, after finding drivers to run everything else, I am at a stalemate on audio. I've tried the original XP drivers, I've tried various versions of the '97 driver, the hd audio driver, Windows 2003 x64 drivers, everything - no sound. Most of the '97 ones say the device is working properly, but still no audio on any device I plug into the jack. I even went into the BIOS and enabled onboard audio (rather than the AUTO default).

I would really like to get this working, as I intend to buy another CPU and more memory for this PC to get the most of it.