Need Toshiba Dynabook SS M37 sound driver?

I have recently purchased Toshiba Dynabook SS M37 from Japan but after adding windows 7 (english), I am unable to find its sound driver (soundmax). I tried many versions but none worked. Please help.

Everythng is working fine including video, mic, lan, wifi, card reader.

Currently I am using USB sound card for AUX port.

Please help