|"With my old video card the sound worked"|
The GTX 460 has a built in HDMI audio controller which may have made itself the default audio device. Right click the volume icon, click Playback Devices, and make sure that "Speakers" is your default device. Disable the nVidia HDMI audio.
2x19A is a little on the low side for a card that needs two PCIe power inputs, but it should be enough for the time being.
"I bought a new video card and when I play SC2 it's still choppy"
"amd anthlon dual core 2.01 GHz"
While you can get away with a 2.6GHz single-core in StarCraft II, the recommended specs call for a 2.4GHz dual-core. Your CPU is holding back your new video card. However, the X2 3800+ is an excellent overclocker, and you have a great board. You should be able to get at least 2.5GHz outta that mofo.
jam will tell you how. I'm going to bed. :-)
Insanely 939 | Dual-core Opteron 185 @ 3.2GHz | 4GB CL2 PC3200 | 1.0TB
A8N32-SLI Deluxe | Blu-Ray | X-Fi Ti Pro | NEW! GeForce GTX 460 1GB