Itanium XP was weird, it's like that super early AMD64 version where more of the OS is 32bit than 64bit, with no high theming.
It was still exciting at the time.
IIRC it was even weirder, because it was a XP branded Server 2003 under the hood.
It's even weirder than that :)
The initial release of XP for Itanium was more or less a stripped down XP build with limited 64 bit support. They then quickly gave up on that approach and released a second version of Windows XP for Itanium, together with the launch of Itanium 2 support, which was, as you said, a rebranded Server 2003.