Have you tried Asus's website? I used to have an Asus video card and that's where I went to get the latest drivers. Don't know the exact address off the top of my head, but it should be something like
http://www.asus.com or easily found through a search engine.
As for best mpeg compression. I've done a lot fo experimenting and the best compressed mpegs (without losing quality), is mainactor's plugin that comes with Vegas Video.