First thing, 20 gig iPod has been replaced by the 30 gig iPod with video capabilities. As a result the 20 GB version's price should go down.
The iPod in the speaker setup is a product designed specicially for the iPod, and as far as I know there is no equivilant for the Creative. Due to the popularity of the iPod, you get access to the hundreds of accessories available.
Many MP3 players can record audio, but neither of the two you've narrowed it down to can (except iPod can with a $40 accessory, actually). The Cowon iAudio X5 records audio I believe, as can the iRiver players.