Arduino as HID

Hi all.

I've hooked up a Qprox capacitance-to-digital sensor to an Arduino board, and am using the setup as a kind of theremin. The sensor spits out a stream of 16-bit data relating to the proximity of objects (like my hand) to its electrode/antenna.

The 16bit data gets sent as ACSII strings into the computer (PC, WinXP) via the Arduino USB serial port. Then, in Max, I can re-assemble the ASCII stream into meaningful numbers and do stuff with them - ie, generate a tone, whatever.

So, here's the problem: It all goes too slow, and half the time everything jams up - Max just doesn't seem to be able to cope with the amount of data coming in, even when i program Arduino to send only 2 numbers per second. Not at all useful considering I need to cut down the latency to below 10ms for the setup to be even vaguely useful as a musical instrument...

What about somehow convincing windows that Arduino is actually a keyboard or a joystick or something, then using the data in a HI object in Max?? Is anyone able to explain to a relative newcomer how Human Interface systems work (ie, how to make something that windows will recognise as one), or suggest other ways to get a fast 16bit data stream into Max somehow?

Thanks, Jon.