Home lawn sprinkler control advice please

Hi all, Just moved into a new home... we've got a sprinkler system for the lawn/flower beds but there are problems with the system. I've gotten several opinions from sprinkler companies in town and they're telling me I need a new control unit. Being a computer geek, I'd love to hook it up to my rig and automate the crap out of it. I've done some searching on the net but am overwhelmed by all the options. I'm great with computers, but not so handy with the handyman stuff. Any advice on how to set things up? Thanks in advance for the assist!!