I agree, go with Gimp, but if you ever are in a place to try photoshop and illustrator, I definitely would! I know my school supplies it for us, so that's nice. I also just got Manga Studio, which was only $25, a lot cheaper than Adobe products. I haven't been able to use it too much yet, but now that it's summer, I'm going to have a lot of fun with it! It has good brush stabilization, so it should be good for mouse users.
As for Photoshop and Illustrator, it's really a style preference.
With Photoshop, you can make something more like this:
http://veszely.deviantart.com/art/Upendi-526608722It looks more painterly as opposed to Illustrator, which uses vector imaging. It allows you to make very smooth shapes, I find it very fun to do! Here's some Illustrator stuff:
http://veszely.deviantart.com/art/Moral ... -525599769 http://veszely.deviantart.com/art/Bored-Cubs-520266613Both are fun, but they get very different results! Good luck! :3