The Startup Wizard comes with a default skin but don't feel you're limited to that look, you're only really limited by your own imagination. The only items in Startup Wizard which are static are the buttons, the rest you can configure however you wish. There are a number of images you can edit in the "Startup Wizard -> Artwork" section but the one which probably has the biggest effect on your look and feel is the GUI Background Image. The default one is rather boxy and quite basic but by changing this image to your own custom one you can get a completely different look and feel, just remember the button positions are static so design around those using the original template provided.
When changing images please make sure you read the comments as some need to be transparent PNG files. This is VERY important, uploading a fullsize jpeg where a transparent png is required could result in the whole screen being taken up by your image making navigation impossible!
A full guide to Startup Wizard configuration: