Re: 2hrs 45minutes and still not done !
"At least you can do an in place upgrade of Windows. Unlike with say Red Hat or CentOS...."
I saw what you did there...
You are perfectly correct in stating that Red Hat require clean installations of each major version of their Enterprise Linux product, e.g. RHEL 5 to 6 (the currently supported versions) and to 7 (the version that will be released next). It is worth mentioning that major versions have a support life measured in decades.
CentOS is of course a clone of RHEL, as are Scientific Linux, PUIAS/Springdale Linux, and Oracle Linux, so they follow the same process.
Minor version updates (e.g 6.2 -> 6.3 -> 6.4 in my case) are unproblematic and occur as a normal part of the software update - I was able to carry on wasting my time on this forum when 6.3 updated to 6.4 on my CentOS laptop, then I was able to reboot into the updated kernel when appropriate. I imagine that systems administrators running production servers will disable automatic updates and will have a test box to check fine details of the minor upgrades.
Other Linux distributions allow in-place upgrades. Obviously when there are major technology shifts it might be better to do a clean install, and some distributions set up a separate /home partition to make this process easier. At least one poster on the Debian forums claims never to have reinstalled since Woody, including in place updates and when changing hardware. He simply makes a tar.gz of the hard drive and unpacks this on the new hard drive and then reinstalls grub and runs update-grub. Some changing of config files is needed (UUIDs). This does actually work, and I have 'swapped' a Debian and a CentOS installation between a desktop PC and a laptop using this method. Saved a lot of time and downloads.
Finally, some Linux distributions follow a 'rolling' model where packages are updated as and when and there is never a need to reinstall. These tend to be enthusiast oriented distributions as there will be issues regarding library compatibility and configuration changes.
I get paid to use Windows, and the techs at work keep our system running very nicely with very little downtime.
At home, the thing I remember most about windows was having to reboot continuously when installing and updating a machine. Interesting to see that seems to have continued.