Best place to get custom ROM's?
Right here on DroidForums. Just go into the ROM section.
Droid X Roms - Droid Forum - Verizon Droid & the Motorola Droid Forum
May I suggest ApeX by Fabolous.
There is a guide in my signature if you need it.
Droid X - ApeX MY ROOT/ROM GUIDE!
...patiently waiting Cyanogen Mod.