I have yet to find that out, as I haven't got my 3500+ yet, but generally speaking so does onboard audio suck. If you care about soundquality I guess you have to buy a Audigy 2ZS or M-Audio Revolution.
I have Nvidia Soundstorm in my current mainboard, but even Soundstorm gets occasionally choppy despite it has hardware acceleration which Realtek doesn't have. I use my M-Audio 2496 I have for music production instead, rock solid audio but no 5.1/7.1. I you wan't 7.1 then get the M-Audio Revolution.
The only onboard audio I've heard which is rock solid, even if not that great sounding, is the C-Media. I have C-Media on an Asrock-board and in my laptop and it's definitely not choppy. I guess tha VIA -Vinyl is also Ok sounding, but there's almost no boards using it because of cost, it has the same chip as the M-Audio cards but onboard.
But there is a possible solution, I've read that the agp-bus taxes the pci-bus because of modern videocards high bandwidth. The solution is to tweak down the agp-bus latency, default is 256, it can be tweaked down all the way to 32 with the right tool. Reportedly a value of 64 generally removes choppiness.
You can find many tweaking tools att guru3d.com