If you've got a surround system on the pc, it's nice to have the THX console, crossover, eq and I love the crystallizer function (some don't).
I can set the distance from me to each individual speaker, the angle each is at from me, set the crossover to maximize the sub and get the crap midrange out of it, use the eq to get the best out of the speakers (I never fell out of love with eq's, unlike most these days)...tons of functions to get the most out of your system that the standard onboard system doesn't even come close to.
Originally, this pc was for home theater type of duty, which is why I upgraded. Onboard was simply dull and lackluster after spending a decent amount on the speakers. The card made it worth while. I'd probably still get one now that this is a gaming rig only after my experience though.
Doesn't even use much in the way of resources, about 10% of what my graphics card uses. Very small footprint.

I only needed the sound card for the gameport. Since gameport has gone extinct, so has my need for a sound card.
But I'm thinking about building a legecy system for Longbow2 etc. so maybe the soundcard will get dusted off along with
the Voodoo 3500TV.

I did have an top of the range X-Fi Elite Pro......I'm now using HD onboard sound and can't tell any difference whatsoever.

This reminds me, every time in the past that I ever had a hard to fix issue with a sim, it always seemed to be something with the sound card.

Card, but only because I've still got an SB Audigy that I can get Win7 drivers for.

Mobo sound for me. Those buggy discrete sound card drivers are just not worth the trouble anymore.

No bugs here.

What about scorpions?

Oh yeah, they rock you like a hurricane.

Computers are so powerful these days that, except a video card (for obvious gaming reasons), one can run everything on-board and still get a good performance out of it.

However, being old school, I like to have sound, video and network cards.

Thanks all for participating! Interesting results, almost down the middle.

I've got an X-Fi Forte in my flagship desktop and an X-Fi Prelude in my XP-era classic gaming desktop. Those are the ones that are actually being used; I still have an AWE64 Gold ISA, SB Live! Value, and Turtle Beach Montego II (Aureal Vortex2) in need of a Win98SE desktop build. (And I still need to add a Gravis Ultrasound and a Roland CM-32L or LAPC-I to that list, probably an AWE32 with the ASP/CSP and genuine OPL3 too.) So far, I've had no serious driver problems in the last two years, though they do have a few quirks. (But so does every other sound card driver, for that matter.)

It's an expectation for me to be able to play older games with the EAX settings turned on, but even more important to me is CMSS-3D Headphone. It's such convincing binaural surround (at least for me; I guess my HRTF matches well with it) that I don't even feel the need for surround speakers and the complications such a setup would bring. It works well with my AD700s, and it ought to work even better when I get my Stax Lambdas (hopefully by the end of the week).

Oh, and in terms of basic sound quality, there is a difference. The analog outputs on my GA-P35-DS3P 2.0 have some rather undesirable line noise (buzzing sounds when moving the mouse and having heavy disk activity, which persists regardless of volume setting) I can pick up with the AD700s. It's even worse if I use the front-panel audio jack, but it doesn't matter what I connect that header to since it's horribly prone to the noise regardless.

Depends on what im building the system for.

Both gaming rigs i've built for my brothers have onboard realtek HD audio, and they are phenominal in movies and games using decent sound systems. and properly shielded from interference, mainly from the USB Header and HDD Lines

My last 2 rigs however both have add on sound cards, one uses a Sound Blaster Live PLatinum 5.1, the other uses a Creative Sound Blaster X-Fi Platinum fatality, both have the 5.25 breakout boxes, as I rely on the extra jacks for audio & video composition.

At some point OB sound got so good and having a sound card became such a hassle that I gave up and started using OB on my PCs.

Things may have gotten better for sound cards but, I have no complaints using on board sound so, I see no compelling reason to spend the extra money.

Not to go off topic or anything, but my point of view is that computer audio stopped advancing such that OB hardware was able to catch up.

I can understand that the "flat" technology available of audio saves a lot of trouble though - imagine if you had as many audio drivers as you have video and controller drivers...

I think this started happening ever since Creative effectively killed off Aureal. Back then, there was actual competition with computer audio, and we've still got Aureal diehards floating about here and there. After that, Creative got complacent. Sure, the Audigy and especially X-Fi lines brought improvements, but nobody could really stand up to them like Aureal did while they lasted, and this is probably why Creative got REALLY complacent after the X-Fi. (Even after Microsoft tried to make their products unappealing with Vista's new sound stack, which is actually an improvement in most regards except that it killed DirectSound3D.)

Sure, C-Media is making headway in the audiophile market (guess whose chipsets form the basis of the non-X-Fi Auzentech, Asus Xonar, and HT Omega cards), but they're not aiming for the gaming market all that much. (Especially not without EAX 5.0 support that Creative won't license out. Sure, hardly any new game uses it to begin with, but I still play a lot of older stuff.)

Then again, how many gamers have speakers or headphones that would make use of better sound cards in the first place? Probably not very many. Audio's treated as more of an afterthought compared to video.

Xonar DG here, onboard was fine up until W7 came changed the way sound is processed and the realtek drivers lost their ability to provide any depth to the sound output. For the sake of a £20 soundcard I'd rather have decent quality sound than the tinny rubbish realtek outputs under W7, unless of course things have changed driverwise in the last year.

No sound card here, I use a SB USB headset: LINK

Best headset I've ever owned, very comfortable and great sound.