What DirectX are you using?
Everquest requires that you install DirectX 9.0c separately. You still need to do this even if you have DirectX 10. Link to Microsoft installer.
if your problem is that the button never changes from "Updating" to "Play", then right click on your shortcut to Everquest, select Properties, Compatibility Tab, Set to run as Admin.
For Vista/Windows 7 users, To avoid problems with over-zealous security, it is best to install to a directory that isn't under "Program Files" - for example "C:Everquest". You should also set the properties of the Everquest short cut so that it runs as Administrator.
http://www.paullynch.org/tnzfaq/Installation:
How can I install Everquest?
How long does it take to download?
How much space does an installation of Everquest require?
Does Everquest run on Vista/Windows7?
I have installed Everquest, but it doesn't work. What now?