Yes, while onboard audio has improved for the most part over the years, a decent soundcard is still the best solution. An onboard audio chip utilizes power from the CPU which in turn can degrade overall media performance especially noticeable in games. Depending on the components used to produce the audio, onboard generally will use cheaper parts as it is more of an afterthought marketing ploy than anything else, trying to give consumers all-in-one hardware solutions.
As for which soundcard to get, It depends on how much audio performance you want and how much money you want to spend. You say you'd use it for primarily gaming, watching movies, and listening to music. Well, that pretty much covers everything you'd use a soundcard for other than MIDI applications.
I would suggest HT|Omega Claro, ASUS Xonar, or Creative Titanium series. May as well just buy the top end and there'll be no looking back. I've heard good things about Auzentech but none of the models they currently offer interest me. I just upgraded from X-Fi X-Treme Gamer card to the Titanium Fatal1ty Pro (which was on sale a few weeks ago @ Newegg) and it is great. I also run Z-2300 speakers and use Shure SRH840 headphones and a Logitech 960 Headset. Everything sounds stellar.
This is next on my list when it's time for a build upgrade. I have heard ASUS and HT | Omega may be introducing new soundcard models within the next few months.
Apologies for the long-winded post. But audio is important to me and so is the hardware that produces it.