I highly recommend that you dual boot. You can learn linux at your own pace and spend as much time in whatever OS you choose. I think that approach is better for new "recruits" rather than the trial-by-fire/sink or swim approach.
That being said, I dual boot Windows 7 Ubuntu on both my laptop and desktop. I spend most of my time in Ubuntu on the laptop, and Windows on the desktop. The ONLY reason I have not migrated to Ubuntu only on the laptop is because Windows is so darn power efficient. With my TimelineX, I get 8+ hours in Windows but at the best, 5.5 to 6 hours in Ubuntu. Powertop is a great utility but its not as good as the built in power saving measures of Windows.
Fedora, Ubuntu, OpenSuse, Mint are all fantastic distros.