Guitar Pro will be good for beginners. It is easy to use and follow. Just download the song's tabs and start playing.
There is TuxGuitar also, is free and can read Guitar pro tabs though i don't know if runs on windows.
You can also search wikipedia for some music knowledge.
Guitar Pro gets my vote too. Its not free however...
I have used Guitar Pro for years without incident. Its running via Wine on Linux without an issue. I am aware of TuxGuitar and know it also happily reads GuitarPro files =)
Tux Guitar can do almost everything that guitarpro can and it's free.
TuxGuitar is an open source tablature editor, which includes basic features such as tablature editing, score editing, triplet support and the ability to import and export Guitar Pro gp3, gp4, and gp5 files. In addition, TuxGuitar can function as a basic MIDI editor using the tablature or staff interface, and as of the 1.0 release, can import and export MIDI files. TuxGuitar's mascot and namesake is Tux, the penguin mascot of many games and programs originally designed for Linux. It is written using the Java programming language, with the GUI toolkits SWT and GTK. Released under version 2.1 of the GNU Lesser General Public License, TuxGuitar is free and open source software.