Hi ChrisYes it is a bit confusing but this is what you should be downloading and installing from eCS:-
IBM CD-RW, DVD-ROM and DVD-RAM File System Support - download update
Release Date: 07-19-2002 02:25:48 PM
Last Update: 01-17-2004 01:56:26 PM
Type: Driver [UDF]
Version: Version 2.1.3
Last update by IBM on 11/26/2003. This software package provides OSTA UDF Revision 2.01 support. The package provides CD-RW, DDCD-RW (Double Density CD-RW), DVD-ROM and DVD-RAM file system support for OS/2 Warp.
Yes, it is packaged as udf201.exe
As mentioned before you will probably need the IDE DASD update as well.
Regards
Pete