Not sure as to Creo, but from a Windchill standpoint, Windows XP 32 and 64-bit are discontinued for Windchill 11.
My guess on timing from that would put Creo support dropped at Creo 3.
Windchill 11 will support "Wildfire 5 & 6" or what is now Creo/Pro 5 and Creo 1. I am guessing that Creo 2 will also be supported with Windchill 11, since it will be out before WC11.
Thank you,
Ben H. Loosli
USEC, INC.