Howdy all!

I'm creating a world for a browser based game. The project is pretty much completely over my head, and I'm trying to break it down into elements i can tackle, one at a time. I'm a complete newbie in world creation, and have pretty much no artistic talents. I have taken some college geology, so I have a basic understanding of how terrain forms and smooths.

What I need:
-Realistic looking world map (this is really the only part that must be realistic)
-Continent, country, and region views (would be best if that could simply be the same map as above, but in higher detail)
-Town/location views - these will be individual maps loaded when a person goes to a given town, dungeon, or some other area. I may generate these with code rather than hand create each one, but either way they will be separate from the main map, and probably in a more cartoon style.

What I have:
-the Adobe CS4 programs (yes, these are legitimate registered copies).
-Bamboo pen and touch (by coincidence).
-Mac and PC platforms, I'm willing to work from either one.
-A few coins I'm willing to toss towards a program if there's a better option than what I have.


What I'm looking for is a recommendations for someone with no artistic talent (I mean NO talent, lol), but time and willingness to learn. I'm willing to try free or paid programs (though free is always preferable), and I'm fine with using more than one for different parts.
Suggestions for software?
Suggestions for tutorials or other things to read?