Microsoft’s upcoming operating system is Windows 7 and we are not going to get it anytime soon. But, if you like to have a look and feel of Windows 7 desktop theme on your Windows XP, just download the theme and install it.Remember that, since not much detail about this upcoming operating system is available, the theme looks very similar to Windows Vista but provide some nice refreshing changes to the same old look. [Source]
To install the theme- (1) Download Windows 7 Theme here, (2) Install "UXTheme Multi-Patcher 6.0.exe" from "UX Theme Patcher" folder. (3) Double-click "Windows 7 M1 VS.msstyles" in "Theme\Windows 7 M1 VS" folder to install.