First of all I wouldn't recommend trying this since it might damage your Windows installation and then you might need to format your hard drive and lose all your files and programs. You need to have enough RAM on your computer and good video card, also make sure that you create a new restore point before installing any of these programs.
Again if you have all your files backed-up and you really want to
make Windows XP look like Windows Vista then you can take a look at
Vista Transformation Pack and
BricoPack Vista Inspirat Ultimate 2.