Just did that a couple of days ago, and I'm not the brightest guy out there technology-wise. What I'm trying to say is that if I could do it, anyone can do it.
Start by visiting the link below:
Droid X
Get to the last part, where it says:
Return your DroidX to stock unrooted 2.1
and follow the instructions. You will lose everything, but not really. If you have appbrain, there you have your list of previously installed apps. Once done, you reinstall them and voila!
Whatever is saved in your microSD card, you have nothing to worry about. I saved all my pics, vids and music in my PC, just in case, but I didn't need it, after this process, everything was still in my microSD card, although I'd recommend you to do the same thing I did, just in case (I'm sure there are other ways of doing it, but this is how I did it and it worked, so I'm happy)
I thought I bricked my phone because it just didn't want to boot, but after some patience, wiping data and cache and batteyy pull X 2, I was back in business. Phone is running better than ever. PM me if you have the same problem and can't get out of it.