I can help you out getting your original xbox controller working if it has been already converted to USB
But I don't think I can post the instructions here because this metod uses a program called" Driver Signature Enforcement Overrider" to allow the device to be installed.
The funny thing is that these drivers are not the Hacked xbcd drivers getting around that require you to mess with your System 32 files (and that don't work anyway), they are digitally signed by Microsoft & they haven't been altered in any way. You don't need to use the "Driver Signature Enforcement Overrider" to install the drivers because they install on both Platforms without any errors or driver incompatibility warnings, in fact they are specifically designed to suit Vista & 7.
But unless you run that program Windows Vista & 7 won't recognize the original Xbox controller as valid hardware, I guess it's because it has been converted into a USB device when it originally was never meant to be a USB device. That theory is just a guess but it is Strange because it's made by Microsoft.
But the problem does seem to be with the actual Controller being recognized as a Compatible device. I think Windows Vista & 7 just don't want to recognize the Original xbox controller as being valid hardware anymore.
But anyway,,,once you actually manage to get it installed Windows 7 & Vista recognize it perfectly every time and they give no errors or warnings at all.
It is even gets listed under Human Interface Devices in the Device manager, so go figure!
But if you want the instruction PM me.
EDIT: maybe I am allowed to post the instructions here,, Mods??? Yes or no???