That's funny. I distinctly remember noticing how those error details frequently "complete" instantly, so I've performed an experiment a number of times:
1) Get the report-crash window to pop up. 2) yank your Ethernet cord / power off your wireless. 3) submit report. 4) "success!"
The only times it's ever sent anything has been when some Microsoft core-product crashed on me, and then you get a progress bar and nearly always a link to info on a (likely) related error. And it catches less than 1/2 of the ones I've generated.