Yes, I'm all too familiar with that messy PBR code.  That's why I was
surprised to find that the first sector of my Windows partition didn't have
it.  As I think about it, I'm guessing this  is because I used FAT32
instead of NTFS.  I bet Microsoft assumes that FAT32 based installs don't
share with other OS's.  Although, "doesn't play well with others" was a
phrase I muttered with my colleagues frequently while  I was figuring this
mess out.
-Brian