virtualbox.org

I want to play old DOS games like Super Tetris on my Windows 7 machine and I need do some testing of Linux apps. The problem is that both hosted OS have much noticeable performance issues and sound drivers can't be initialised which means that hosted OS can't produce any kind of sound... I'm using Win 7 Home running on Intel Core 2 Duo CPU. Any ideas how to fix that?

Minimum information needed for assistance.

Oups Here you go:
VirtualBox version 4.3.20 r96997
RAM: 64 MB (DOS), 1024 MB (Linux)
Video memory: 15 MB (DOS), 24 MB (Linux)
Host Sound Device: Windows DirectSound (both)
Sound Card: Intel HD Audio (both)

I am using MS-DOS v6.22, Linux is not installed yet...

I can't find High definition Audio in the menu, though...