Indeed you can attach a mouse and keyboard to a iPad, but it will is not needed if you use voice recognition which can turn your voice into text, but you need a very clear and easy to understand voice.
This will also be coming to the PC, and Mac, so this means that Windows XP and older computer with 512MB of RAM a slower CPU, because Window 7 is being ran online on a powerful server instead of installing it on your actual computer.
I bet in the future there will be a similar program which lets you use Linux desktop operating system online on Onlive.