Sorry, I never saw your post to get back to you! The iPod runs on either USB 2.0 (not sure if you still need a kit or not), or the more standard to Apple, FireWire 1394. The Dell runs on USB 2.0. After a long order delay with Dell and a lot of screaming, they finally shipped my Jukebox and I received it today. I'm thrilled with it. The battery life and screen are better than the iPod, and it's a great player, especially for $100 less.
For FM transmitters, the Belkin Transcast is the brand of FM tuner that Dell supports and recommends. FM transmitter is just the general product. The Apple plays MP3 as well as AAC (an Apple format), but they play MP3. The Dell plays MP3, WMA, and WAV. I think the iPod might support WAV as well, not really sure.
As for the USB 2.0, the cards are really cheap (probably around $10-$15), or you can just back it down to USB 1.1 (it's backwards compatible), which would run slower, but it's still speedy. However, the USB 2.0 is really fast. I was able to sync most of my music collection in under ten minutes. I prefer FireWire, as I have a FireWire/USB 2.0 PCI card installed, but USB 2.0 works just fine.
P.S. The Dell also features a voice recorder, if that's something that's important to you. You can record and then playback on the hard drive of the player, however you can't upload them to your computer. However, you might be able to if you buy Dudebox Explorer from Red Chair Software for $25, but I'm not sure. To voice record on the iPod, you need an external accessory.