A pretty decent isometric attempt. However, did you save that image as a JPG file? I noticed it is a PNG, but was it compressed by a program in some way? The texture on the faces of the gamecube are quite grainy. If you added the noise yourself, that's a really terrible way to texture something. Though if it was compressed, you're probably best off using a program such as GraphicsGale to save it as a quality GIF file.
Keep it up.