folder is because you have skipped the necessary files. The CD contains more files that tell the OS how to continue than the folder shows.
See here where they explain bootable CD's.
http://www.techsupportalert.com/search/t1214.pdf
Hope this helps.
i have my windows xp disk when i make a backup copy disk to disk using nero 7 the copy works 100% fine the disk is bootable and i can make a new installation.but the problem is that when i copy all the files from the windows disk and saved it in a folder in my computer then i make a copy from that folder using nero 7 or any other software and the copy is fine but disk wont boot it become not bootable.if i do it disk to disk it is fine so what you thing is wrong.it does this with my pc and my laptop and my friends computer.thank you

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