encyclo - 5:25 pm on Dec 15, 2009 (gmt 0)
I've just done an upgrade from Vista to 7. Things were going smoothly until we had a power cut more than two-thirds through! But when the power came back on, the system quietly and automatically rolled back to Vista and I was able to restart the installation. No damage, no files lost. I'm extremely impressed by how smoothly it went.