1. Do you install drivers after or before windows 7?
You install the drivers for Windows 7 after the installation. You may need to install some drivers at the beginning of the installation if you have a RAID or unusual SATA controller.
2. Is there a fix for error missing installation files?
If you get this error half way through the installation procedure then you either have a faulty installation media, a faulty CD drive or faulty memory. My bet would be the installation CD is faulty.
Well, The CD has worked before, and the installation disk is burned, so I dunno. I formerly had windows 7 32-bit, and I'm sure the memory works as the BIOS recognizes the 8GB of ram (2 sticks of 4gb), and is there a way to fix it?