A few more thoughts on op-scan machines...
In Wisconsin, if there is a recount, the original machine must be used and the ballots are not allowed to be hand counted to confirm the machine. If the machine counts the ballots the same each time it is considered accurate. So, if the proprietary code (which we and our election officials are not allowed to see) has been hacked to switch every 10th D to an R it will do so both times and will result in a verified correct re-count.
Here's some info on recent problems in Michigan with op-scan machines:http://www.bradblog.com/?p=9487
We've effectively privatized our elections and given up any effective oversite. Why anyone believes "just trust us" when it comes to the most important aspect of having a democracy is beyond me... Especially with all the evidence that elections are stolen on a regular basis.