Perhaps too late, but I would highly recomend ARES by mj12 games.
Fast, adaptable, generic. you can do anything you want with it and it handles it all.
Barbarians vs. undead, Musketeers vs. Beholders, Mammoths vs. Dwarves, all no problem.
We've even adapted it to Wild West Skirmish and Sci-Fi games with no issues.