If you're going to acquire software to produce graphics, then GIMP might be your best choice. It has 99% of the functionality of Photoshop, at a GNU price (i.e. only how much your bandwidth costs).
Adobe Illustrator is hard to beat for vector graphics. Corel Draw isn't bad, but it is very different from Illustrator. Given the price differential, if you're buying Draw, you might as well get Illustrator. AFAIK, there are no decent GNU vector packages. If you're shopping for Draw, you used to be able to buy the Draw enging "i.e. the program" without all the clipart, in a package with other Corel software, for much less money.
Bob