We've got a lot of frequent city mappers on here. I've done one and am working on another. Gandwarf (right?) a master of City Designer (a plug-in for Campaign Cartographer)...and that might be an option for you if you're not quite ready for Photoshop/GIMP yet.

Take a look at my current city's WIP thread here:
http://www.cartographersguild.com/sh...723#post107723
It started as shapes in Illustrator (you could do something similar in Inkscape, which is free) which were easy to draw and position. Then I brought them into Photoshop and used textures and filters with a little bit of hand masking and layer blending to create the buildings. I think this is a pretty powerful process for creating a city quickly. Though this particular map has been in the works for four-ish months that is mainly because of lack of time to work on it. Once I had the shapes drawn it was quick and easy to get the basic buildings pulled together in PS.

Much easier than my first ambitious city map, which was hand drawn, scanned, and then painted in PS. Hundreds of hours in this one:
http://www.cartographersguild.com/sh...r-by-mearrin69

So. Anyway. Don't let Photoshop scare you off. Let's see what you can do. Start with a town, though. Really. Start with a town.
M