The server is going to be held back to 1.4_01 until all Bukkit and some of the more important plugins update. Do not update to 1.5, If you want to update but would also like to log onto our server you will need to go to .minecraft folder which is usually located in "C:/Documents & Settings/"name"/.minecraft.
Copy the .minecraft folder onto your desktop and keep it there to copy back when you want to downgrade back to 1.4_01. Where I put "name" I have SiKiN, just to give you an example.
Easy now, SiKiN.
