Just browsing your website, namely the 'My Perfect PDA' page. I got one of these a couple of weeks ago...
The device uses IrDA, Bluetooth, WiFi, CSD and GPRS for communication choices. It has a 400MHz X-Scale processor and 128MB RAM. It also has a SD I/O slot and a built-in VGA camera which can take photos and video.
MP3 is no problem and it even comes with a pair of stereo headphones.
For me it was a perfect replacement for the Treo/iPAQ. I now only have the one device on my dashboard where it takes the roles of handsfree phone, SatNav (Tom Tom Navigator 3), Traffic Master (Tom Tom Traffic) and GPS speed camera warner (Checkpoint).
I'm currently using a bluetooth headset but I have a Sony Ericsson HCB-300 bluetooth carkit ready for when I get my new car...
You should give one a go :)