I've got a decent comp, and even though WoW is old, it's got some updated graphics, which, in raids, etc. could totally kill a computer.
Drop shadows, AA, spell effects, etc. right down to minimum is what we used to tell people in our guild who were constantly crashing, and you'll find you have a much easier time.
Also drop any unnecessary mods that you may have installed. It's surprising how much of a difference it makes.
Playing in full-screen seems to help some people, I find that the game is just 'nicer' to play in Windowed mode. Lets me tab out to do other things when I'm not actively doing something.
I have a DESKTOP with integrated graphics. Most of the options you told me to turn down don't even allow me to alter them. I have the game running in almost the simplest graphical qualities for everything. The only thing that I have higher are environmental detail at high and texture resolution at good. Distance at fair. I know that is a big factor but it looks horrible without at least decent draw distance.
Environment detail probably won't be helping your cause with onboard graphics, and I'd probably drop Texture Resolution down to Bad until you get a real graphics card.