You can download a set of the Vista icons that were made to be compatible with Windows XP here http://vistaicons.com/
Note - they are all individual ".ico" files, and go up to 48x48 pixels only.
I am not sure what size are being displayed in the screenshot (perhaps larger than 48x48), but IconX looks to be in use to enhance them.
i am using this pack right now - unfortunately, i do not think you will find it on wincustomize - i do not remember where i found most of it at - but i have changed a few icons in it and repackaged it for myself. i don't know if they would let me post it up on wincustomzie or not.... maybe i'll try 
WinVista icons A deviation by ~tutituti
http://www.deviantart.com/deviation/22012147/
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