Have you installed the latest drivers? If not, I would suggest you start there as the CD contains old drivers.
Here is the latest Intel Chipset drivers, install this first then reboot and install the LAN and RealTek drivers then reboot again
Intel INF Chipset (Multi OS, x86/x64)
Software License Agreement
LAN And RealTek (Gigabyte page)
GIGABYTE - Support&Download - Motherboard - Driver - GA-EX58-UD4P (rev. 1.0)
RealTek, pick the drivers in Audio from the Top two choices, depending on your system x86/x64
LAN you want the second (last) LAN Driver download for Vista
If you still have sound issues or LAN after this please post me a expaned image of your Device manager, and then also post a image of your Sounds window from Control Panel and I will see if I can help you with your Sound issue.
As for your LAN, if this does not fix it for you please post for me what BIOS settings you are using per LAN in the Integrated Peripherals BIOS page