ARDUINO MIDI over USB for a Worshop

Hi all!!
I'm sorry to open a new topic on this arguments, but none of the other topics helped me :frowning:
I was used to have Roland SERIAL MIDI Driver convert data sent from my arduino 2009 (and a couple of IR sensors, slider,pots... connected to it) to the pc (and then to Ableton & friends) , now i bought an arduino UNO and the roland trick seems not to work anymore, at least on windows 7 !
I have to find a way to have arduino communicate directly over USB, as i will be leading a very-basic introductory workshop on arduino + MIDI ,
and i need a quick and easy solution to let every attender run the code on his pc!
So i have to discard HIDuino (as flashing firmware and so it's not reccomanded on an introductory course :smiley: ) , and i want to avoid any external / user programmed serial To Midi converter, as i made some in processing or other language, but i still get much more delay than using the roland serial midi driver on Arduino 2009!
Any help is appreciated!!

Well, the main difference between Duemilanove and Uno is the USB interface, so it's not surprising that a serial interface doesn't continue to act in the same way.
I wouldn't expect the same results from the USB interface.
Duemilanove boards are still available (and being discounted) so you should try to get some.