Hi - short-time reader, first-time poster.

I ran into a problem during method 2 of this great guide that I was able to fix, but it isn't mentioned in the guide so I thought I'd post it here and then hopefully someone can add it.
The problem relates to the, "Error loading operating system", message that may appear after the first restart during the XP installation. I followed the advice in the guide to fix this but nothing worked. Eventually I figured it out myself: my motherboard (Gigabyte EP45-UD3P) has the following BIOS setting:
- SATA RAID/AHCI Mode
I had this set to "AHCI". After changing it to "IDE", XP was able to install just fine. After that, I was able to fix the Windows 7 bootloader per the advice in the guide and all was well.
However, changing this setting in this way means that you obviously lose the benefits of AHCI in Windows 7 (including TRIM support if you have an SSD, for example). Also, if later on you change this setting back to "AHCI", your XP installation will fail to boot, so be aware of that. If, however, you don't have an SSD and don't really care about AHCI then this fix will work fine for you.