In The Dark for Windows XP is free software supported by donations, not advertisements. If you find this software useful, please support it!
In The Dark has been ported to Windows XP, so you can keep your screen clean of bubbly aesthetic whateverness, also known as Luna.
As always though, Microsoft did a hack job at theming, and a lot of things will look really bad with black backgrounds and white text. I've tried to circumvent it as much as possible with the dark gray backgrounds on some windows, but many applications are simply written poorly.