The best way to get a Windows 7 look on a Windows XP install would be to upgrade the Windows XP to Windows 7. But since not all users want to upgrade to Windows 7 due to compatibility reasons, many users would like to get the shiny Aero theme introduced with Windows 7 on Windows XP as well.
There are very few themes that can bring the Windows 7 to look to Windows XP. But recently, I came across a theme for XP, which exactly matches with the Windows 7 theme (see the screenshot below).
Windows 7 theme for Windows XP
You will get close Windows 7 look for your XP with this brilliant theme. Ernasco from deviantart has created this beautiful theme. The taskbar may look small compared to Windows 7’s superbar, but it looks really good with the small icons.
If you haven’t upgraded to Windows 7 yet, this theme will give the exact Windows 7 look for your Windows XP. However, note that you need to install WindowBlinds software to use this brilliant theme on XP. You can download the trial version of WindowBlinds from the below link.