The fact that the screenshot is fine and that you get it in safe mode makes me nearly 100% sure it's the monitor. (Which isn't fun, because they're more expensive than entry-level graphics cards.)
That being said, if you can test the computer on a friends' or parents' monitor, it'd help a lot to diagnose the problem. Failing that, can you describe the problem with as detailed an explanation as possible?
(Oh, and don't worry - you're WAY more tech-savvy than most of the people we try to help.)