Blessed Assurance

In my copious spare time, I have kept my eyes out for software that meets the following conditions: allows a way to write music, provides playback, preferably with multiple instruments, works on a PC, and is free. This one may just be my speed. I consider it "not too shabby". Fairly easy to learn, and all WYSIWYG. A few aspects are still a little clunky, but it could be me or the fact that it is a relatively new website.