In the process of trying to downgrade my iPhone I installed ReadyDriver; not really sure what I was doing, but now when Windows 7 loads, none of my devices respond. I can boot into WinXP fine and access the drive, and I have EasyBCD, but I don't know what to do - there is no RD entry in the bootloader and I removed the 'boot' folder from the drive with Win7. Do I need to edit the registry, and if so, can I do that from a different operating system (namely, XP)? I would really like to be able to use Windows 7 again.

Well, RDP doesn't change any Registry entries, only the bootloader. I have heard of the disappearance of the USB devices, its seems to be an unknown bug in RD/RDP for some people.

To truly purge any bootloader modification, follow these instructions by Microsoft:

http://support.microsoft.com/kb/927392

It has commands to completely rebuild BCD, and the MBR. RDP only messes with the BCD. If rebuilding the BCD does not work, it is a problem other than RDP.