Each to their own: The many Linux distros have a massive following, but come in flavours from the high-level (eg Mint, which a total dodo can use "out of the box") through to heavily cut down ones (low-level) that can be infinitely customised in every single respect.
Upsides: Free; Customisable; Much Support; Great Fun
Downsides: Whilst there are Applications covering most functions you'd expect from Windows Programmes, there are some notable omissions. In some of the latter cases, there is a feature called WINE that enables Windows Programmes to be installed. But not always, and not necessarily with ease.
For that reason, I dual-boot the Crunchbang Distro (Low-level) with Win 7 on my Netbook, so I can carry on using Microsoft Money (The best Programme they ever made, yet sadly no longer supported).
Horses for courses.
But if you want to try without risk, many Distros can be burnt to a Live CD or Live USB stick that you can Boot from directly without touching your Hard Drive.