Why oh why did you reformat... I guess ignorance is bliss. You didn't really HAVE to do that.. but too late now.
That error just means exactly what it says. NTLDR is missing. NTLDR is a file on your C:\ that contains the boot loader. Hense the name NTLDR = NT LOADER. Usually this happens when people carelessly delete files, or there is some kind of virus that deletes the files (less likely).
Did you change anything recently? Add new hard drives? Install a new app? Browse any porn?
You could have copied the file from your windows xp CD to the C:\ within the repair console on the setup disk.