Re: can't boot to Windows 7 anymore (dual boot)
when your computer boots, bios reads the first sector of the disk, which tells it what to do next.
for xp, it passes control to boot.ini, for vista/win7 it parses the "bcd store" (boot configuration database)
when installing multiple OS's, install your older ones first, then newer, then newest, to preserve backward compatability.
i havent worked out the details of repairing yet, but if you search for BCDedit you may find more useful details.