Aside from the technical issues(different drivers required for different motherboards), what you are asking is not legally permitted. It violates the M$ license agreement.
If you are talking about an application(not the operating system), you would still need to un-install it from the first computer, and then install it on the second. Installation makes changes to the registry that can't be copied. Sorry!
Just to move a program you can't copy most of them, you need to re-install it on the new computer. There are some programs that attempt to do this, can't say how well it works. http://www.spearit.com/about_MoveMe.html, maybe a few more like that out there.
To clone a whole disk onto another system means you are moving the entire drive over, including licenses. If you do that, you can only use one of the computers, the other one has to be wiped. Also their hardware has to be similar or it won't boot.