I dont have an X but if you're asking just in general...I've had 2 android phone, both have been rooted and I've ran so many different roms and variations and version of android that I cant even begin to name them all.
Simply rooting the phone isnt going to change the way it runs right off the bat. Rooting it will however allow you to run some apps that require SU(super user - root) permissions. It will also allow you to flash custom, modified roms. If you flash a buggy rom, your phone will be buggy...Different roms will give you different options and looks, etc. You are going to probably want a stable rom, the experimental ones are called experimental for a reason.
I'm not sure what all is available for the X, I have a nexus one and I have more options than what there are N1's around.