Cannot get two audio outputs from one soundcard

Recently I purchased a new headset.
It connects to the computer through two 3,5mm jacks, a mic out and a sound in. (Never buying anything without USB again...)

My regular speakers are also connected through a 3,5mm jack.
I've attempted to keep my speakers plugged in the rear and my two headset cables in the front, but the sound out simply switches from rear to front.
What I need is two different outputs, one for my speakers and one for my headset (TeamSpeak usage).

So far as I've searched and tried it seems only possible through the Realtek HD Audio Manager.
Here's the kicker: I have an NVidia soundcard, and after 2 hours of rebooting, re-installing and browsing countless threads, I've come to the conclusion that I am completely and utterly UNABLE to install the Realtek HD Audio Manager.

So what I'm looking for:
a) Some way to get Realtek HD Audio Manager installed successfully.
b) Some way to get two unique audio outputs from one (on-board) soundcard.

The answer to b) above is to use a two way adapter like this:

You can only have one default audio playback device. Thus you can only get one output. If you have two different inputs it will be mixed together.

The one default audio playback device is a Windows limitation.

You MAY (note MAY) be able to do this somehow with two separate sound devices (cards).

Quote: I've attempted to keep my speakers plugged in the rear and my two headset cables in the front, but the sound out simply switches from rear to front.

I think you will be able to ahieve this by changing a jumper on your motherboard. Check out you motherboard documentation for this! I would have looked this up for you but was unable to do so as you haven't completed your system specs.

There are jumpers that join different parts of the onboard audio and it is possible to change the order but don't touch it unless you know exactly what to do! I would suggest that your best course of action would be to go onto the Asus website and go to the support section. I have only seen the UK version but it is very extensive and that looks the best palce to seek the answer.
try this link:
http://support.asus.com/ContactUs.aspx?SLanguage=en

Lets us know how you get on. I'm sure it can be done as I have an old self built PC that I configured to emit sound from both speakers and headset at the same time but cannot remember the procedure. It's probably slightly different to your motherboard anyway!