Glittering Eye points out that, between capturing a terrorist and capturing a terrorist's computer, the hardware might be the better choice.
Securing Zarqawi's computer and the information in it may lead to identifying his sources of financing and his operatives as effectively as actually capturing him might. Possibly more so — I know that there's stuff in my computers that I don't have committed to memory. That stuff that Zarqawi has in his head might have a pretty short shelf life and be pretty tough to get out. Meanwhile, soon enough there'd be another Zarqawi running things and he might be somebody that we have far less information about than we do Zarqawi.