Internet Explorer 10 (IE10) will support only windows 7 and later versions of windows. So, IE 10 will not have support for windows XP and windows vista.
If you install IE 10 platform preview program on vista or XP, you will get following error message.
Windows Internet Explorer Platform Preview does not support any operating system earlier than Windows 7.
You can find the minimum system requirement for IE 10 in Release Notes.