I'm lucky in that I only have to support the Server versions of the OS. We have Win2k3 x86 and x64, and Win2k8 x86 and x64 both installing from Winpe2.1 x86. See this article: http://support.microsoft.com/kb/925279/ For Win2k3 we use the winnt32.exe for a network install, but most of those are captured to a WIM for a syspreped deployment. And Win2k8 we also do network based installs, as well as syspreped WIM deployments also. I would try out those switches in that article and see if they also work for XP. You may get lucky. If not, I'll see if I can find any of my old notes on multi-boot winpe2.1 and pxelinux.