How to edit Windows 7 logon screen and general UI

Is there a way to create a custom Windows 7 logon screen and UI? I don't mean just customizing the picture, I mean something in the sense of a flash splash screen on a website. And then having the whole UI cu开发者_运维技巧stomized in the sense that, instead of a start button, I have can have like... a plus sign that opens up a customized start menu.

Is there anything in the Windows GUI library that will enable this? I know quite a few languages except for assembly, not sure if it would require that anyway.

In other words, if you go to www.sony.com you see how it loads up? Is that possible in a Windows environment? If not, where or how could I do it in another environment? Thanks!