Ah, thanks. Hm, now I've got to ask you another question. So, on the subject of photoshop-type programs, which one would you recommend? I'm wondering about how I should go about getting involved with map making, and, well, the edges thing is really a bit of an irritant at the moment - especially since the setting I was thinking of doing a map for has more puppet states than the average!
Well, anyways, thanks for your answers, and thanks in advance about the new one.
I use Adobe Photoshop for these sort of things, and a word of warning: it's complicated to use at times for fine details. It has a lot of different tools, but due to it being 'better' the brush tool fades from the center to the background color, so if you're doing borders in that program, be aware that they will not be clear and sharp, unless you use either a very specific brush (which I'm not aware of), or use the Pencil tool.
Thande's method of Paint like programs are simpler tools, but much more versatile in this arena, and if you are more familiar with it, I'd recommend them over Photoshop, as that takes a bit of time to learn.