No, because Pandora uses a different type of CPU that is incompatable with XP. Send Microsoft an email asking for an ARM port if you like, but it's extremely unlikely they will humour you.
Well, I was going to half-jokingly flame you by pointing to Windows XP Embedded - but even that doesn't run on anything but x86. So I'll simply say "You are right about no XP, (which is what the OP asked for) - but there is Windows CE, which does run on ARM. Still - good luck getting Microsoft to let you have a copy made for the Pandora."
Sometimes thinking about what you're going to say, and confirming your assumed knowledge *before* you post actually does help. I learned 2 things today, and it's not even 10AM.