Okay I wonder if I can forget the RS232 stuff because its worthless to me anyway in this project, and just write some code for the arduino to look at data coming in from the PWM pins -- I really could use a logic analyzer but the salae logic is like $199 which is a little out of my range right now (saving for a house down payment this year). I'm going to write something to monitor the D+/D- lines and see what I get. I dont know for sure if I can make a tight enough C++ loop to get down to the 4us range, but it wouldn't hurt trying either.

I dont know what I was thinking trying to wire this up 232 style. Thanks for turning me in the right direction.