installing and using a linux,say Ubuntu helps.u may need 2-3 weeks to get a hold on linux very well if ur a windows power user.
http://ubuntuforums.org and other forums like this forum can help u.
Linuxmint(ubuntu+codecs) is good if u want to have multimedia support by default.using bash terminal is a necessity in Linux.but UNIX CLI is very easy to learn compared to DOS.every commands are documented under "man" for eg:
"man cat" or "man tac" will give the details of command and usage.also bash shell is sophisticated enough to complete the command by pressing TAB twice.
I'll suggest read:
http://getgnulinux.org
before going for Linux.also if expecting alternate windows in Linux,then Linux is more similar to Mac and very different from windows.
if u want alternate to windows then try
http://reactos.org
GNU/Linux is much more userfriendly now and 3D effects and eyecandies way better than aero is there(compiz-fusion).there are many window managers and Desktop Environments(Gnome,kde,Xfce etc) to choose from.stick with a Debian based distro like Ubuntu for easiness.even non-debian distro Fedora,opensuse all are nice,but package(s/w) management is a pain.
Debian is a Free Operating System-
http://debian.org
best of Lux