Can anybody please tell me how to get the original XP logonUI back on?

Thanks in advance

-Simon

Look on your XP disk in \i386; there should either be a logonui.exe or logonui.ex_

if it's logonui.exe, just copy it into %windir%\system32, reboot, and there you are. If it's .ex_, then rename it to logonui.cab, extract it, then put the resulting logonui.exe into %windir%\system32.