If you are using WMP9 and Windows 98SE don't waste your time with this codec. Once installed you should be able to see a DVD option in the Play menu and in the Tools>Options>File Types menu there should be a check box for DVD video but neither was present.
I cannot see how any of these free MPEG2 decoders could possibly work since the media players with DVD playback capability are programmed to recognize only the main commercial software decoders like NVIDIA and PowerDVD. Anything else would require tweaking of the registry which is a skill beyond the average user.
If you want a free DVD player take my advice and use Media Player Classic. It works a treat with XP as long as you have a 1 Ghz or faster processor.
GPL MPEG-1/2 DirectShow Decoder Filter 0.1.2 on 20 January 2006, reviewed by: Anonymous