If you cannot get enough of Guitar Hero while playing on your home console then Frets On Fire is a great way to get a similar experience on your computer. Frets on Fire is a cross-platform Open Source project.
You can download and install Frets on Fire on a Windows, Linux, or Mac OS X box. There is also a portable version which ensures you can get your guitar gaming fix any where there is a computer.
By default there are only three songs to choose from but there is the ability to import songs in OGG format as well. A site that has a bunch of ready to use songs is Keyboards on Fire. Just download the zipped song file and extract it to Data Settings Songs.
The default keys for frets are F1-F5 which might might be oddly placed for some players. Just go into Settings to change the fret keys on the keyboard to what you’re most comfortable with. Also, I was able to get a Logitech game controller to work on the Windows version.
To start off it is a good idea to run through the tutorial to get a feel for the controls.
If you are a fan of Guitar Hero or have never played it before you will have a lot of fun playing Frets on Fire. For additional support and new songs check out the community site fretsonfire.net. For a bunch of new songs to play check out Keyboards on Fire.