Absolutely that helped in gaining a wider audience. But I suspect the reason yahoo chose google was because all their tech people preferred google because they all used it to search for code. Maybe it's my high school or my college, but google won over the CS crowd very quickly. Their clean interface and their ability to get the code we were searching for to help us with our homework really gave them a leg up.

Then their gmail ( especially the initial invite and storage ) and chrome made google the "cool" tech company and pretty much cemented their place in the tech world. Sadly, they've turned out to be monsters rather than saints and we are all the worse off for it.