NOTE: Please create a Restore point using "System Restore" before applying anything mentioned in this tutorial so that you can restore your system back to default if you don't like the changes.

After following this tutorial, you'll get the same Windows 8 look in your Windows 7. Following is a list of things which are going to change after following this tutorial:

Windows Theme or Visual Style
Icons
Boot Screen
Login Screen or Welcome Screen
Start ORB or Start Button
Sounds
Cursors
Ribbon UI in Windows Explorer
Start Screen with Live Tiles
Wallpaper
User Picture Tile in Taskbar
Aero Auto-Colorization Feature
Centered Titlebar text, icon and Up Button in Windows Explorer
Windows 8 Watermark on Desktop
Extras

So without wasting time, lets start the tutorial:

Windows Theme or Visual Style

Recent Windows 8 builds have featured a new Aero Lite theme. We have shared lots of themes for Windows 7 which provide similar UI.

You can download your desired one using following topics:

Icons

Currently Windows 8 icons are same as Windows 7. We'll update this section as soon as Windows 8 comes with new icons.

Boot Screen

You can get lots of cool Windows 8 metro boot screens for Windows 7 using following links:

Login Screen or Welcome Screen

Windows 8 login screen looks very simple and doesn't provide any eye candy effects as shown in following screenshot:

To get Windows 8 login screen in Windows 7, check out following article:
Download Windows 8 Login Screen for Windows 7
To get the date and time on login screen, check following topic:
Download Windows 8 Metro Logon Clock Screensaver
You can also check following awesome Windows 8 concept login screen for Windows 7:
Download Windows 8 Concept Login Screen “Gloosh” for Windows 7

Start ORB or Start Button

Windows 8 comes with a new start button:

You can get this Start button in Windows 7 using following tutorial:
Get New Leaked Windows 8 Start ORB (Start Button) in Windows 7

Sounds

Currently Windows 8 sound scheme is same as Windows 7. We'll update this section as soon as Windows 8 comes with new sound scheme.

Cursors

Currently Windows 8 cursors are same as Windows 7. We'll update this section as soon as Windows 8 comes with new cursors.

Ribbon UI in Windows Explorer

Windows 8 also features Office 2010 Ribbon UI in Windows Explorer. You can get the Ribbon UI in Windows 7 Explorer using following article:

Get Windows 8 Look-Like Ribbon UI in Windows XP, Vista and 7 Explorer using Styler Skin

Start Screen with Live Tiles

Microsoft has featured a new Start Screen in Windows 8 which looks similar to Windows Phone 7 home screen. It basically shows live tiles of the installed programs in Windows 8.

You can get it in Windows 7 using following articles:

Wallpaper

You can download some cool Windows 8 wallpapers using following links:

User Picture Tile in Taskbar

Microsoft has integrated Windows Live service in Windows 8 shell. Now Windows 8 shows user picture tile in Taskbar notification area.

You can get it in Windows 7 using following topics:

Aero Auto-Colorization Feature

One of the most interesting feature of Windows 8 is "Aero Auto-Colorization" which is the ability to automatically configure the color of Aero elements, like the Start Menu, Windows Explorer windows, and the taskbar based on the desktop wallpaper.

You can get the same effect in Windows 7 using following free tools:

Centered Titlebar text, icon and Up Button in Windows Explorer

Windows 8 Explorer comes with good old "Up" button in toolbar. The Explorer window also shows titlebar text along with icon in center.

Windows 8 Shows Centered Titlebar Text, Icon and New Up Button in Explorer
You can get the same in Windows 7 using following tutorial:
How to Get Windows 8 "Up" Button and Titlebar Text in Windows Vista and 7 Explorer?

Windows 8 Watermark on Desktop

Watermark aka Windows build number is shown at the right-bottom of Desktop in Windows testing builds. You can get Windows 8 watermark in Windows 7 using following topic: