XP Bar Addon?
 

Any mods/addons that will show the xp bar on the main screen?

I think a lot of custom UIs have this, the one I use (Haeldar) has an exp bar that gets replaced by the target bar when you target something.

I think the VeliousV3 UI has an XP bar inside your char window. You can download it from the Getting Started guide here http://www.project1999.com/forums/showthread.php?t=2651 (see Step 3 - Done! Launching, Playing, and Optional Improvements)

Savok's VertUI
http://www.project1999.com/forums/showthread.php?t=7850