PC Software Question about Unistaller?

[SayITasITis!]

Is there a program available that you can put onto a brand new pc that will then monitor all software that you install so that should there be a conflict it will protect the pc and registry and if and when you want to unistall a software it will unistall it completely thereby hopefully leaving the pc in great almost brand new condition? For example if i wanted to put a computer game onto my pc and then take it off without it slowing down my pc or messing it up in anyway?

If there are any free programs like this then ofcos please let me know

thanks x