Ive installed vista business on

Question

ive installed vista business on my acer aspire 8920g and i had to remove all the previous acer files and such and i went to the website and downloaded all the drivers but now my screen resolution isn't working i have a 18.4 widscreen and it's only at 1280x800 resolution, and i am supposed to have 5.1 cinematic suround sound but i only have sterio recognised on my comp also my screen is very dim and i can't find anything to change it.... can you help ? please