I just reformatted my computer...

You should not skip any files during the Windows installation, if it is skipping, check the actual disc for scratches/dust - if the disc is clean, then the problem tends to lead into hardware problems (I had this happen once on a friends computer, he was unfortunate to find out it a faulty RAM problem - but that's what you get from scabbing RAM modules from thrown out school computers :P)

Yes, all files on the windows installation disk are important, if they were not, they would not put them on the disk. Check the disk for scratches, and and clean it if need be. try again, and if no go, then do some hardware checks..there is a memtest program, that you can run to test ram, and im sure there is a hard drive tester. if none of that fails, buy a new install disk.

Here is the mmtest program: http://www.memtest.org/download/1.70/memtest86+-1.70.iso.zip download, and unzip, then burn the .iso to a disk, and run it on startup.