I found mercurial much easier to learn/explain than git (the hg team seems to be more interested in keeping its public interface clean), and it has TortoiseHG (http://tortoisehg.sourceforge.net/) on Windows. (There are several other graphic interfaces available: http://www.selenic.com/mercurial/wiki/index.cgi/OtherTools)

This book helps, too: http://hgbook.red-bean.com/