the usb dongle and the etherdongle can be used to output either pixelnet or dmx. you have to choose one when loading the firmware.
that being said, if you choose dmx, there's no way to get pixelnet from either.
but, if you choose pixelnet, then the only way you can get dmx, is through the output of a active hub.
ok, about the dongles themselves.
if you go with the EtherDongle, the advantages are... most sequencers seem to operate more smoothly with the EtherDongle.
plus, the EtherDongle is easily upgradable to the use of add on cards (conductor, slave, etc...) thus, you wouldn't even need the computer except for sequencing the show in the first place, and setting up your schedule. Also, the EtherDongle supports over 16k channels(in pixelnet mode) before you would need another dongle.
To make the jump from a DMX only show to add pixelnet.
You would need...
1.)the ability to update the firmware of your dongle (or even to program a new dongle) to pixelnet.
2.)a 16 port active hub (to support your DMX gear).
3.)a pc power supply to power the active hub (must be a single rail for the 12v output)
4.)1 or more Smart string Controllers if you're powering smart strings (12v lights listed in the wiki that have an IC in each node to control the led's)
5.)1 or more dumb string controllers if you're powering dumb strings or strips (12v common anode {+} lights where they don't have an IC, and you're controlling the entire string or color as one channel)
as for what to make, the possibilities are endless!
