Enterprise Server Version and Service packs

Hi everybody,
We are currently running
Enterprise Server Export version 4.0.4 040301.
My question is which service packs/patches
I should apply to this server? The ServicePacks
page lists the following servers and 4.04 is not
in the list:

Enterprise Server 4.0.1
Enterprise Server 4.0.1 Export
Enterprise Server 4.0.2
Enterprise Server 4.0.2 Export
Enterprise Server 4.03J
Enterprise Server 4.1
Enterprise Server 4.1 Export

Any ideas/tips are appreciated.