Earlier quoted context omitted.
To be fair, what percent of Windows users could actually install the OS if they needed to?
Not sure I understand the question, you mean could they install Windows on the same machine? It was running XPsp2 prior to Ubuntu 9.04.
Installation is an obstacle for linux adoption, but it's not (entirely) because the installation process is broken. It's because Linux doesn't have the OEM distribution model that Microsoft does.
I don't think this refutes anything you've said, I'm just pointing out that it is more than a software issue.