Historically, I've cautioned Windows users against upgrading from one version of the OS to another, because the result is often a crufty, Frankenstein-esque install that doesn't run as fast or reliably as a clean install. With Windows 7, however, I've been forced to reevaluate this advice.

In the process of documenting the various ways in which one can install and upgrade to Windows 7 for the forthcoming book, Windows 7 Secrets, I've discovered that the upgrade process appears to work a lot more smoothly than it did in previous versions. Now, I'm not ready for a blanket reversal of my previous advice. But I've now upgraded three heavily-used and constantly updated Windows Vista-based PCs, and one XP-based PC, to Windows 7 (in additional to numerous, less relevant virtual machine installs).