Small revision:

I finaly got conformation from a guy who has both, a 3400, and a 3500, that the batteries are in face interchangable.

the good news is that new/OEM referb batteries are available for the 3500, i just got one, 149 shipped.

Add that to the device and the replacment HD i ordered, and the WiFi i had, i have a very usable pen computer fo a bit under the theorhetical $500 budget.

Givent the chance to do it all again, i would go with the Mid-Range ones being offered (139) and use a USB: hub, keyboard, and mouse for installs, as now that mine is setup, i plan on putting the dock away forever. That could bring your affordable "Pen enabled slate computing device" in at a pricetag of way under $400