Might have been a typo, but they no longer sell the IIIx; this has been replaced by the IIIxe and now the m105. Anyway, I started out with the IIIxe and loved it, but didn't like having to buy batteries all the time. I then upgraded to the Vx b/c of the rechargeable internal battery (and it looks cool). I now have a Sony Clie, which is pretty much the same as the Vx but has a memory stick slot. I got a good deal on the Clie, which was why I got it, but it's pretty cool. They have a new one coming out at the end of the month that has an MP3 player built in, in addition to a high-resolution color screen.
Unless you need the wireless capability, don't get a VIIx unless you really want to be able to browse the net, or you have cash to spend, or you want to pay $50/month for the wireless service. With any of the other Palms, you can use a modem with infrared, or a data cable, and go on the net.