Onboard Audio
Audio Chipset
Realtek® ALC892 8-Channel High Definition Audio CODEC
ASUS Noise Filter
Supports 192khz/24bit BD Lossless Sound
Supports Jack-Detection, Multi-Streaming, Front Panel Jack-Retasking
Optical S/PDIF Out port at back I/O
Thats in the motherboard specs. All modern motherboards come with some sort of soundcard either onboard or some motherboard manufacturers will give an expansion PCI E card. The realtek should be fine for what you described you want it doesn't sound like you an audiophile or anything since you are asking for the cheapest solution.
So try the onboard out I bet you will be more then satisfied with it onboard sound has come a long way in the past 5 years.