Barneys,
My vote is for an iPad too.
Re: downloading photos, get yourself the Camera Connection Kit for the iPad - makes it as easy as pie. Best $35 you'll ever spend.
Re:wifi vs 3G - you say your dongle is a wifi one? Ie, you don't need to plug it in, you just connect to its wifi network and it works (like a mifi hotspot thingy)? If so, the wifi iPad would do fine. It you've got a smartphone that can share the Internet connection, you can use that too. Ie, my ipad can connect to my old iPhone via Bluetooth, and use its Internet connection.
The advantage of the 3G iPad is, as the others have said, not needing to worry about any of this - it just works. Plonk the sim card in it, and then use it whereeever you are. Plus, it's got the gps receiver, if you ever wanted to load up the hemp maps app for it. $150 for the pre-paid Telstra iPad sim is pretty good value.
I have a wifi iPad, and wish I'd paid the extra for the 3G model.
It's one of the best things we've ever bought, especially when travelling. Not cheap, but great.
Good luck!
Matto