I just started fooling around with gimp and let me tell you its ****ing awesome. It's just like photoshop $-600. Even if your not an artist you can create some really cool **** with this heres one of mine and keep in mind i just started and am not good at drawing and or painting. Heres a link to dl for windows.
http://www.gimp.org/windows/ Have fun and let those creative juices flow.