I tried drawing in PowerPoint once long ago and hated the interface so much that I swore never to do it again. I'll do simple shapes there if I need them for a presentation, but I make anything more complex in Illustrator.
Take a look at Inkscape—it's open source vector drawing software. It's nowhere near as powerful as Illustrator (yet), but it's got all of the basics, and it can produce some very nice results. Be sure to go through all of the tutorials before you decide whether or not you like it.
What year will this map depict?