I need some help finding the correct graphic design software/freeware.?

I am looking to create posters/prints/flyer's for music, sports, etc. To be eventually printing on docu-color printer most likely via .pdf format. For example like a 28" x 12" small concert poster. That I can make using a variety of fonts, clip-art, imported images, drawings, etc. to Create them and maybe eventually sell. I'm a creative artist on a budget that needs to make some extra cash, not to mention I also love making the artwork. I eventually plan on doing this full time but don't have the money for the software, schooling, etc. So basically if you could recommend some type of freeware/openware/etc. that would be great!! Comparable to something like illustrator, photoshop, etc... what I'll eventually have to get i'm sure.