You cannot downgrade Windows 7 to XP. If you want to use XP you will have to do a new install
Just be sure to save all your documents, pictures, favourites, music .... to an external; device like USB memory stick first
If you want to make Windows 7 to look like XP then you can follow the given below steps
Windows 7 is a great new operating system, but some people may not be comfortable with the new interface or the taskbar. I will show you how to quickly and simply configure windows 7 look like Windows XP.
Windows 7 is faster than Windows XP and it's got a great new user interface that most technicians love. If you don't like the efficient new interface of Windows 7, you might feel that you are out of luck. However, there are a few ways to remedy that situation.
Here's a quick guide to making Windows 7 look and act a bit more like Windows XP.
1. Changing The Taskbar : –
One of the biggest changes to the look is Windows 7 ‘Taskbar’. It looks cool to us, but it's definitely very different from the artistic of Windows XP.
Simple steps to changing taskbar:-
Right click on the Taskbar.
Then go to Properties
Then go to setting
Then change the setting marked Taskbar Buttons to Never Combine.
This will make the Taskbar more like as the Windows XP designs that we are all familiar with windows XP. You also need to choose "small icons", and right click each icon to "Unpin" it from the taskbar. If you want to change it back, just reverse the steps.
2. Choosing the Windows Classic Theme: –
As per my experience enabling a classic theme, you will truly get Windows XP.
Steps to choose Windows classic theme
Right click on a clean area of the desktop
Then go to Personalize
After that under Themes, choose the 'Windows Classic theme'
Then click on ‘Apply’ then ‘Ok’
This makes your theme and folders look like they did in Windows XP. Folders will show up more usually, as will icons on the taskbar. There are still some big differences from Windows 7 and Windows XP, but this clears up most of the major ones.