I've recently received Beta 2 and so as not to mess with my XP Pro install, I have attepted to install X64 on my second Physical HD where I have/had XP Pro 64 loaded for testing. After the first installation failure, I tried to load my standard XP Pro from the first Physical HD all to no avail. I have attempted to use the recovery tools and get no further than the Boot selection screen. The Vista 64 cannot repair the boot , and neither can Vista 32. The message indicates a CorruptBootSectorCode.
I have, however I have replaced the boot.ini using a bootable floppy and also replaced NTdetect.com and ntldr, and have access to my system again. I'm getting a new system soon and may wait off loading it till I get the new system. Nothing to loose on it. I may try on a smaller HD temp replacement of my main.