Do you like Mac OSX? do you want to have Mac OSX style in windows? if yes now you can have it in win7 too! our best friends sagorpirbd ported Snow Leopard visual style for windows 7.
This is a really nice and same as the real Mac OSX theme.
You need to copy theme in C:\Windows\Resources\Themes
For using this theme first you need to Patch Uxtheme.