Let me share my experience. I also had difficulty making audio and sleep work.
First off, please be sure to check the motherboard's version. The OP's motherboard is an old one (rev. 1.2) with Via VT2021 codec on it. Mine is rev. 1.3 with ALC889 codec.
Do not install VoodooHDA if you have rev. 1.3. It strangely works on rev. 1.3 in the first place but you will see very frequent kernel panics. I just installed a generic USB sound card bought off from eBay at $2~, which works great. Just disable the on-board audio.
Sleep is a hit-or-miss but it works only by keyboard or mouse which is hardwired directly to M/B, not to a USB hub or wirelessly. My Logitech wireless combo has never waken it up.
Installation was rather tricky. It never went through with my video card installed. Thus, I had to boot with on-board VGA (with -x option). Then, I ran MultiBeast (transferred from a USB stick) with a downloaded DSDT. After that, I installed my Zotec GeForce GT220, and, then, voila, it went through.
Ethernet did not work so I downloaded Atheros AR8151 kext and installed it with KextBeast.
I have struggled with the ACL889 for a while with every single kext combination but no success. So I installed a USB one. I disabled sleep and now everything works beautifully. Very stable so far.