Well I definitely like what you got so far. It's not the final draft for sure, but it's getting there! So here's what you need to do, and I'll suggest some methods of fixing them up.
-Boring background, a dull blue doesn't work well with so much action in the foreground. Your work will look much more professional and better if you do something about whats behind the images.
-Hiding the text can be good, but in this case I personally think it'll look much better shrunk down so no characters touch the letters.
-Where's the SNK characters?? ok, thats just a personal preference
So I have a few suggestions you can try, here's an easy way to make a nice marble background, you can use this on the gradient and it'll look really, really cool, ok in photoshop, do the following:
Select the background layer with the gradient
Filter : Texture:Grain... (doesnt matter much intensity)
Pixelate : Crystalize...
Image : Adjust : Hue/Saturation...
now when the Hue/Saturation window comes up, click the colorize box, notice how the background has now become marble looking. In the step of crystallizing, the size of the cells can greatly affect how much like marble it looks. Just find what you like.
After you click the colorize button, change the Hue to what you like, if you give it a nice blue hue, and turn down the saturation. A very nice background that looks good on almost any image.
-Luke
ps: if you want some other cool effects, check out
www.photoshopcafe.com I made up that marbelizing affect the other day, but its easy to follow