Flowstone as a hardware music synth

[Tronic]

maybe this
http://www.stickpcstore.com/stick-pcs/i ... orage.html
but you need an HDMI monitor, and as Myco said, it lack on native Asio driver, so you have to use the Asio4ALL, but this not guarantee the best performance for small latency.

[MyCo]

Intel Quark SOC might work, they have a Pentium Core... but 400 MHz single core, single thread is just way too slow. The stick is a lot more powerfull. I would go for an A4-5000 Board, as they are dirt cheap and extensible. eg:
http://www.asrock.com/mb/AMD/QC5000-ITXPH/
Thats about 70€ in Germany... needs some RAM, a drive and PSU, though

[alphaOri]

As far as I can tell, one can't even get a copy of Windows Embedded Standard unless you buy a piece of hardware with it pre-installed from an OEM...

EDIT: Whoops, nevermind. I found you can download the toolkit and an evaluation image (180 days) for free. See this vid (https://www.youtube.com/watch?v=gxhg4Th1Ufo)