Adding a background color statement won't affect the speed with which it loads all that much, one or two milliseconds at the most, and the file size is barely any larger.
Originally posted by Wes DeMoney
Yahoo is designed for speed, performance, and compatability. And that is why they have not set a background color. Check it on a text browser, its a sure bet that it looks exactly the same just w/o images. Look at how fast it loads. Yahoo also leaves the links to standard colors I think. The reason it is grey is because you have your default background color set to grey. If you don't like the grey, change it to white. Yahoo! is actually a good example of a well designed, compatible, corporate site.