Windows Vista Aero is a graphical ice candy interface introduced in Windows Vista. FastAero is a free utility for Windows XP that adds Vista Aero like enhancements to Windows XP. (Via gHacks)
FastAero is a portable app, so you can try it with out installing. It adds Glass effect to the windows. The default language for FastAero is Polish, but you can change it to English, the option is in config.ini file.
Download it if you want to get some eye candy to your Windows XP.