I got this elsewhere for you.
I guess the best way to fix Windows faulty boot is to insert your Windows XP start up disc. After the utility loads up (the famous blue screen) select the option to repair. Go to the command line and type chkdsk /f or you may let Windows fix the problem automatically--this option is before you get to the command line. If chkdsk /f does not help, try chkdsk /r
Usually when Windows XP cannot load, inserting the start up utility and letting it to fix Windows files only it will leave all other data intact.
Give it a try.