I havent gotten my X yet, hope someone will be home today to accept it....
If u are rooted, OC'ed running Froyo, using Launcher Pro or ADW, speed wise it should be on par or better than the X right now.
Some things I'm sure will make a difference:
The X has 512MB Ram vs. 256MB on the Droid
The X uses LPDDR2 memory vs. LPDDR1 on the Droid
The cpu is already running at 1Ghz on the X vs. OCing to 1 on the Droid.
The Droid is waaaay more customizable right now since it has root and u can run custom ROMs. If u have a rooted Droid, unless u want the hardware advantages of the X, the Droid can keep you happy if u thinking about the X.
The Ram and memory differences might start to show later on tho. And when I get mine, the only thing that will make me keep the X is if it has better reception.
If it doesnt, my Droid will keep me satisfied til LTE phones come.