You can't. You could set Google as default in IE, so instead of the current steps of 1)press magnifying glass, 2)type in search bar, 3) press enter for search, you will instead have 1)press IE icon, 2)type in address/search bar, 3) press enter for search on Google. Essentially making no significant difference.
Although, Bing is actually pretty good, at least for regular search stuff. You'll get used to it in no time.