In searching for some good multi-track music recording software, I recently came across Acoustica Mixcraft 5:
http://www.acoustica.com/mixcraft
I recently bought a copy, and I'm fairly impressed with it. It has ease of use comparable to Apple's Garage Band, but is available for Windows. Similar to Garage Band, it includes virtual MIDI instruments and allows recording & mixing of both virtual MIDI instruments and audio tracks. I'm fairly excited about it!
Nightfox