Hex Grid, GIMP, and you...
If you are going to get GIMP (and I'd also recommend it. You can't beat free!), you can create a Hex grid of just about any size you want to by doing the following steps:
Open a new picture in GIMP with a white background. Make sure this new picture is the same size as your original map, and choose black as your foreground color.
Go into Filters --> Distorts --> Mosaic. Choose the following parameters:
- Tiling Primitives - Hexagons
- Tile Size - Whatever you need it to be (up to 100 max in my version)
- Tile Height - 1.0
- Tile Spacing - The thickness of your lines. Depends on the size of your original map and your preference
- Tile Neatness - 1.0
- Light direction - doesn't matter for this case, since the tiles have no height.
- Color Variation - 0.00
You should get a nice hexagonal grid in your new image. Once you have that, go to the Colors menu, and choose Color to Alpha. Choose white (it should default to white). This makes all of the white in your picture transparent, which will leave you with only the black hex grid.
Select all (Control-A) and copy (Control-C)
Now open up your original map. Go into the Edit Menu, and select "Paste as New Layer." That will create the hex layer over your original map. Save it down as a jpg, and you'll have your map with a hex grid. Save it as a default gimp file (.xcf extension), and you will be able to play with your map underneath the hex grid.
Hope this was simple enough, and that it helps you out!
Thumbnail of map with hex grid
I ran through the steps I mentioned above, and I ended up with something that looks like this for your second map:
The full size picture is here These were done with a size 1 thickness grid.
For paint, that is a very nice map!!