Integrated sound vs sound card?

I am buying a new computer. I already have a 140 watt Logitech sound system. I use my computer primarily for work and music Do I really need to buy a sound card to get the most out of my sound system? I would like to just get something with a good integrated system. I am looking at the Gateway LX6810 Desktop Computer which comes with

Audio Chipset: Dolby® Home Theater™
Will this complement my Logitech system?

Sometimes on board sound is very surprising for sound quality. I would try it first and if you don't like it then you can install a dedicated sound card.

I use a Creative Soundblaster X-fi series card with my Logi Speaker system and will blow the ears clean off of your head without distortion if you want it to.