Need some advice, Is onboard sound good enough?

I'm building a new system and would like to know how good the quality is with on-board audio. The mobo im getting is the MSI K8T Neo-FIS2R, the website has this for the specs on its audio:

Audio
• 6 Channel software audio codec Realtek ALC655
• Compliance with AC97' v2.3 Spec
• Meet PC2001 audio performance requirement
• Provide onboard SPDIF out

I was thinking about getting an Audigy 2 ZS, but if im not gonna see that much improvement from it, then there is no point in spending $90 for it. I mostly game(which means 3D surround is very important) with my computer, but want to be able to listen to music and watch DVDs when I want to also. I use a headset almost all the time(Plantronics DSP 500) but also have a speaker set which I got like 3 years ago but it is great IMO, 4 speaker + subwoofer. Any advice would be great.