I can remember one ATM in Hoi An, it was enclosed and safe but I have a feeling it was out of order when we tried though.

Are you just planning to go to Hoi An? I actually didn't rate Hoi An at all. It's great if you want a suit or a dress made up, a pair of shoes etc, but aside from that there isn't a great deal to the place and it is very very touristy. In saying that there a few good restaurants and the people as a whole were extremely friendly but I enjoyed Saigon, Hue, Hanoi and Halong Bay far better.

With regards to currency we found that local currency was far more common than expected, and considerably more than in Cambodia where the US Dollar rules. In truth though we just got money out as we went along (Nationwide Flexaccount card, no fees), as the ATM's were plentiful in the major cities and it felt far safer. We did book a flight from Hanoi to Hong Kong on Vietnam Airlines whilst in Saigon and we paid for this in USD (great fun changing local currency to USD in the bank!!) but I can't remember paying for any meals or drinks in USD, except when we had cocktails in the Sheraton with our group in Saigon.

Hi,
we actually enjoyed Hoi An the most from our trip around Vietnam.
We had US Dollars and GB Pounds and were able to change both currencies into local Dongs.