Re: Front audio connection
Ah, I think I know the problem here. I found this one when trying to connect my Creative X-Fi to the front panel connectors as it had the same 10 pin arrangement on it.
Intel introduced their new HD Audio codec for onboard sound and they updated the motherboard headers, which is incompatible with the AC97 header that went before it. It sounds like you've got a case which has connections for AC97 and a motherboard with connections for HD Audio.
Re: Front audio connection
This link has some info - which states that the headers should be compatible, but not all functuiosns will be supported. (You need to scroll down the link a bit to get all the info)
HD Audio Standard Motherboard Header - Core system - PC Hardware
Re: Front audio connection
I'm pretty sure my motherboard had a similar arrangement but had schematics for both pin layouts and a jumper to force it to AC97
or something like that.. :)