When I plug in the Uno (tried multiple cables, btw) it says "Unknown USB Device (Device Descriptor Request Failed)" under "USB Controllers." If I say update drivers and select the C:/Program files(x86)/Arduino/Drivers folder it says "The best driver for your software is already installed." I guess it doesnt recognize a usable driver in the drivers folder.
So, next I say "Let me pick from a list of drivers" -> "Have Disk" -> and select the program files (x86)/arduino/drivers/arduino.inf file. Then it says "The folder you specified doesn't contain a compatible software driver for your device. If the folder contains a driver, make sure it is designed to work with Windows for x64-based systems."
That's what I thought, but I can't find any 64-bit drivers. I did some research and found 64-bit FTID drivers but they didn't work either. Do you have a specific link for Arduino 64-bit drivers?
You might be encountering this problem due to the older drivers for Arduino not being signed.
The solution for the same is (A little bit of googling would have helped you here), to Log into WIndows with Driver Signing Enforcement turned off. Due to being lazy, i wont be providing the steps here (Sorry for that).
The second solution to this problem is, to use the newer versions of Arduino software. For example, The Beta 1.5.7, contains newer drivers that are Digitally Signed and do not require you to Log in bypassing Digital Signature Enforecement. You can download that version and install the drivers and see if that solves the problem.
I have already tried disabling the driver signing enforcement and installed the beta.
This is obviously not the problem though because my error does not say (unlike all the others) that "The third-party INF does not contain digital signature information." Also, in the readme of the 1.0.6 IDE, it says the included drivers ARE digitally signed. A little bit of googling would have helped you realize this.
UPDATE: Something is wrong with my board, I borrowed a friend's and his worked right away. Any clues as to what it is? Do I need to reinstall the firmware or bootloader or something?
I am having the same problem as you and like you completed the same steps to no avail with windows 8. The arduino works fine on my Linux machine so I doubt it is the arduino. The issue is with Windows not wanting to install the drivers for the device. The eventual solution needs to be a sticky post because this is an issue alot of people are having.