I think that we could always use more speed and a veteran 4th outfielder in case the Biggio experiment doesn't work. I just would love to have him pinch running for us, occasionally leading off, or just coming off the bench every now and then. He's a hall of famer and is available for the veteran minimum... at the worst he'd draw a couple of walks.
I won't flame you, I mean, even at 43 Rickey's not a bad player, and can be useful in platoon situations. However, I do not feel that at his age he's a significant upgrade, if he's an upgrade at all, over our other outfielders, especially considering he no longer hits for any power at all.
You just described Brian Hunter, who's got a $1+ million guaranteed deal for this year. The 'Stros have enough outfielders; if Biggio fails in CF, Berkman'll move back there.