That's an incredibly weird choice for a logo. I mean, its not the WORST they could do, but it looks like a square simon says. Yeah I know before it was the same color scheme but now they're just sitting there with a perfectly straight negative space and I just this random urge to push the buttons to make them light up. Windows 8 just looks uninspired. Hey guys, if your way of communicating the name "windows" in a logo is literally a window with its borders converted to negative space, then you're not playing the brand recognition game right. Seriously. People look at the apple logo and go "Oh, its an apple." They're going to look at this, pause for a few seconds and go "Oh. Its a window. I get it." Its the bad pun of logo designs.
Windows 7 edited quickly for flat colors and no shadows. Obviously not cleaned up for smooth lines or anything, but its the basic idea. Also it's not really possible to have a flag shape with straight lines? I assume you meant you wanted flat colors/no shading. The whole point of a flag shape is to NOT have straight lines, otherwise its just a flag lying flat which is boring to look at.
