To clarify how well diablo 3 runs on intel graphic i have d3 at 1366x768 with high textures and everything else on low.
using intel hd 3000 on my laptop. the cpu is an i3 2330m and i have 8 gb of ram
it runs ok. i don't have any slowdowns in d3 at those settings. i also play starcraft 2 with it same resolution except everything is on low(1v1s anything else is too much).
my laptop cost 330 dollars. Just to put things in perspective.
i do not suggest getting an igpu like me if you want to play more intense games like battlefield or crysis or even basic games like fable 3 (i barely hit 30 fps on the lowest settings) but if you REALLY need a cheap laptop a lenovo b570(what i have) can do basic gaming.
it does school work just fine.