I'd like to ditch the wall-wart power supply. Anyone ever use one of these to power their arduino project?
I've not used that particular converter, my projects have all been 12V or 24V native, so I would generally use either their R-7809 which is the 9V replacement for the 7809. They also have an R-7805 if you want to go straight into the 5V port. Have never had a bad Recom product.
5V @ 400mA is certainly enough for the Arduino in what you've chosen. Just keep the power budget in mind as you go adding gizmos.
I have use the smaller 24V to 5V module.
If ditching the wallwart, are you running from battery? 3 AA batteries will supply 4.5V, just fine for 16 MHz operation.