Installing a new system will mean some disruption, so you can talk about
* how long before the system will be operational after its installed
* time - how long it takes to install the system
*r isk of failure.. and how failure will disrupt the system
and compare how much disruption different methods of implementation cause..
Meh this sounds all so BS to me *memories of english*
	
	
		
		
			So it doesn't extend beyond that?
		
		
	 
it probably does... have a look in the textbooks, that's where I got my info when i was studying 
