No audio device output

Do really need help.

my comp was ugraded from xp to vista. well,before this it was spoilted and my uncle upragded it this way. And yes,there is no device output installed @ the loudspeaker icon. Not only that is gone,but my microsoft words office software,and movie maker is gone too.I followed some of the advise here,such as going to device manager etc,but mine is like this,

(+)sound,video and game controllers
- VIA AC'97 Enhanced Audio Controller

there is no like some of you mention of high definition etc. when i click on the properties and disabled and enable it too,it was the same. Can anyone help me here? Im kindda desperate as i have to get it fixed back due to projects that require sound (movie maker) . Please help me ,find a solution. And my comp is acer fyi.