MP3 player manufacturers, including Apple Computer, Dell and Hewlett-Packard, are challenging a [URL=]recent regulatory ruling[/URL] in Canada that would impose an extra fee of as much as $25 on iPod-like digital music players.

A group of retailers, including Wal-Mart Stores and Best Buy, also is appealing the decision, which will be heard by a federal court.

Read more: [URL=]CNet News[/URL].