First of all... look at Bush election, years counting and people end up in doubt. Paper election HAVE problems so it isn't in vain to try electronic elections.
But... how a blind will vote in a touchscreen? What if it is "miscalibrated"? IMO what should be done is like in Brazil:
- Open source machines. Everybody with some knowledge can see the code they are running, of course there will be some bugs, but with the time, things are going to be fixed. If you want to have a company behind the elections, it have to follow several laws and mandatory use only open source software, should open it's capital, etc... If no company private wants to do that way, so the government should create one.
- Buttons. So you can feel the click when pressing, and it can have a surface blind-friendly.
The two first elections in Brazil had some problems, but nowadays it is going pretty smooth, very few cases of machine misbehavior... The greatest problem is people trying to steal using other methods, like buying voters.