Hi
If you have a restore point before the problems started try going back to that.
A video card would help, but cost a large percentage of what your computer cost to start with.
Wow is very easy to run, it will run on almost anything so I don't think that's the real problem.
Try updating your drivers especially the video drivers, new computers don't always come with the latest ones installed.
I'm not sure about the buzzing sound, if it wasn't there to start with it could indicate a problem but it's hard to say what.
There is always the chance of a bad component in a new computer.
Mike