I need to draw some diagrams of the combat grid and miniatures for our combat system. I believe I need an illustrator program to do this. But we can't afford adobe illustrator. I have INdesign and GIMP. Does anyone know where I can get an inexpensive or free illustrator program that can handle this task.

Since you don't specify which OS you run, I'll just assume you use a Mac. Some choices:

Inkscape is free (and actually cross-platform) but fairly terrible, IMO. If you love using GIMP (that is, you have a high tolerance for horrible user interface) it might be what you need.

DrawBerry is free. Never used it, though.

Skencil is written almost all in Python, and mostly targets linux systems, but can probably be made to run anywhere. Never used it either.

VectorDesigner is not particularly cheap (USD70), but it is pretty nice.

If you're not using OS X (and, yes, since you didn't specify which OS you are using, that means you probably really aren't), the Wikipedia list of vector graphics editors may be of more use.

Also, if you really just need combat grid like stuff, you might try any of the numerous apps specifically for that purpose, such as Dundjinni or AutoREALM.

I use a PC. Sorry, should have specified.

AutoREALM is for PC, and it's a pretty neat mapping program. It's for PC.

For more general vector drawing, you might try the free DrawPlus 4 (or the $10 DrawPlus 6).

For diagrams, the Draw component of OpenOffice is actually pretty good.

Dia is also meant for diagrams. I tried it a few years back and abandoned it in favor of OpenOffice Draw because I couldn't figure out how to label the connections between boxes. That might be fixed now.

I know some people who swear by Embedded Vector Editor. I haven't tried it myself.