What is difference between 3 apps

I downloaded Connect My Mac for iPod Touch/iPhone. I like it very much. I almost bought it, but then I saw that you have another program called Connect Desktop that does the same thing. And then I see a third application called iRemote Desktop. All of these applications say they will connect to Mac and PC. Which one should I buy? What I want to do is to see the screens on my two Mac and two Windows computers, and I want to be able to control them remotely from my iPod Touch (3rd generation). Thank you for your help.
John
John