ARES: Miniatures Wargaming System is a complete skirmish-level fantasy game published by Majestic Twelve Games. I have heard many good things about Ares. The flexibility of the system allows players to use any wargaming miniatures in their collection. Over two dozen sample figures are detailed in this book, but the real strength of ARES is its figure creation system, that encourages players to use their imaginations -- which is the way it should be!
Also included is a fully-customizable magic system, providing players with the opportunity to design their own spells for their troops. Best of all you can download a demonstration version of the rules at the Ares site.