I was lucky enough to get one of the Acer 1420P convertible tablet/netbooks at Microsoft PDC 2009. Yesterday, the AC adapter died. Since this isn't a model that was sold through normal channels, different find-your-adapter sites give varying answers as to what might work.
I picked up a Rocketfish Universal Adapter today, since one of the tips appeared, through the packaging, to be a match. Works like a charm, laptop is fully charged, and I have a bunch of other tips handy when something else dies.
You'll want the MT32 tip (included), by the way.