 On the DIY side, there's companies like Mr. Cool that have systems that are designed for do-it-yourselfers. The lines are pre-charged, so if you're handy, you certainly could do that yourself, or you could hire a pro. Now, if you want to go with a conventional system, you could do that as well. The difference there, though, is you have to run the ducts. If you don't have the duct system in, that becomes very, very difficult and expensive. So if you've got a duct system, then I think you may want to lean more towards the conventional because you're really just adding to the system that you have.