WMP MPEG Layer-3 option missing

Following a reinstall of Windows XP Professional, Windows Media Player is missing the MPEG Layer-3 option, Tools>Options>Copy Music>Copy Settings.

I used the Dell Reinstallation CD to install Windows XP Professional onto a second hard drive, that I installed following Dell technical support said that I should back up and reformat the original hard drive, following problems with an inaccessible task bar.

I know that there are plugins that can be purchased to add MP3 and have purchased one for another computer but would like to reactivate the MP3 option that still exists on the old hard drive that I havn't yet reformatted. I hope to eventually solve the task bar problem and have the option of being able to boot from either hard drive.

Microsoft Knowledge Base Article - 306494 talks about creating a registry key but I don't know how to do this. Even if I did this, would it solve the problem or is there a simpler solution?