From what I know, the kernel in Etch (and many other distributions) lacks support for the ICH9 chipset of that motherboard, Sid support it, not sure about lenny.
There's a Etch version patched using the 2.6.23 kernel that has support for that motherboard, a friend of mine with the same motherboard said that worked, but if your choice if you want or not to try it.
Here's the download page. Of course, you can still try the Etch version without the patch and see if it works for you.
Regards