According to the AP, the Kent deal is for $18.2 M over two years (plus a $9 M option/$700 K buyout for a third).
That's quite a bit for a 34-year-old player that no one else seemed interested in signing. I'm not saying that Kent won't be worth it, but it does make the move a bit dicier.
I do have to hand it to the Astros: in a year that harkens back to the halcyon days of collusion, they did get a premier player when everyone else was twiddling their thumbs. If Biggio has a comeback this year, the move will look trememdous. It he doesn't, it will be hard to hide his offense in left. At least it beats talking about divorcing the team from the Enron name like last offseason.