It's been a while/ Crackdown & Halo 3 or Guitar Hero 2?

I havn't written a blog post in sooo long.  I've been busy with school and playing games rather then writing about them.  The biggest thing that has happened is that about a month and a half ago i got a 360!  It's an amazing console, and I could talk all about it but you get the point.  Anyway, I've been playing Gears alot and am looking to either get guitar hero 2 or crackdown (with the halo 3 beta of course).  I would like some insight on which to get first.  Ah it feels good to write a blog again!