Post a screenshot of what you are doing (modding related).

[protox]

The skins would not fit properly if you rescale to a different aspect ratio, you would need to reskin the base skin to make everything fit and it would be difficult to skin because the skin's aspect ratio looks very stretched under 512x512 resolution. It would be much easier to downsize back to 320x200 for people with very low end systems. But if you want you can give it a go, I have released the PSD files, it would take some work but it's possible to recreate everything.

Here is an example of what happens when you resize from 640x400 to 512x512. Just one example of a minor issue with resizing to a different aspect ratio.