PhotoPaint is a fine program for mapping. I started out with it, and kept with it until I moved to Photoshop for school. For buildings, I had good success with Duvik's tutorial here: http://www.cartographersguild.com/showthread.php?t=716 Get textures from cgtextures.com And the Zombie Nirvana tuts I pointed out in your intro thread are also quite valuable.

If you're comfortable with Corel, I say stick with it. It's quite a powerful suite, and familiarity is valuable. DRAW is also nice for more illustrative maps like this one: http://www.cartographersguild.com/sh...?t=2439&page=5

That one was done with Serif DrawPlus, I think, but CorelDRAW is a comparable tool.