I'll put in my 2 cents worth. Both of those sprockets are visibly worn. Should they be replaced? It depends on how the bike is going to be used. If you don't put many miles on the bike, the new chain and old sprockets could give you years of service. This may not be you, but a lot of people I know don't put 2000 miles a year on their bikes. If that is the case, no sweat. If you are going to tour or do a lot of commuting, especially if you do it in crappy weather, I'd replace them as a set.