Migrating from Windows - Finding a Distro

So I'm considering switching to Linux, however I am admitantly computer ignorant. For this reason, I'd like some help. I will probably converting multiple computers, for multiple users, so I'd like something that is close enough to windows that my parents won't go into complete shock. Additionally, we transfer stuff to and from each other through our wifi connection, and Vista has been very simple in this regards, so I'd like a system that we'll make these exchanges easy as well. Finally, I'd like to test drive any suggestions, or in otherwords I'd like to be able to choose on boot which system I run. Any suggests for distros, or generally useful information, would be appreciated.

Thanks for any help.