Worldguard vs. GriefPrevention

I've been managing an SMP server that has basically been an anarchy up until this point. Now the players want some way to claim land/protect their bases. I know of both Worldguard and GriefPrevention as big land claim plugins, but I have never used either and I don't know which one has the functionality I need, or if I need both.

Advice is appreciated. Thanks.