Re: USB/Volume/Power switch panel, personally I wouldn't, because I tend to like my builds simple and child/drunk people/idiot proof, so normally I put all my "admin" controls in a spot that isn't directly accessible. But really, it's a subjective matter, so you gotta think about what you really want for it.
That being said, since this was posted in the artwork forum, I'll just comment on the art.
I think you're on a really good track here. There are two things I would do to it to really get it cohesive and pro-looking.
1. First, fix the font size. It looks like you're scaling the 16-bit font vertically, so it's getting a stretched look. The original Genesis's 16-bit title didn't look so narrow.
2. Shadowing, and Highlights.
Take a look at this genesis picture:

Notice how there is a highlight (and fade) on the rounded front bevel of the genesis' base? Also how the rounded area of the cartridge slot is shadowed and highlighted, giving it that 3D effect of depth.
I believe your artwork could use this to really push it further. Try choosing a light direction and adding some highlights to the edges, while adding shadows to the parts that are supposed to be extruded out.
The theme is solid, it just needs a bit more to push it to a completed cohesive state.
