What do you mean, "upgrading"? The only reasons there might be to change those parts would be: 1) you want to change gear ratios; 2) some parts are worn;or, 3) there is no 3.

First step would be to check the chain for wear. Measure from the center of a rivet on the taut chain using a good steel rule. 12" along should be at the center of another rivet. If that rivet is in fact at 12 1/16" + then you need to replace the chain before it grinds your cogs and chainrings into scrap. If the rivet is at 12 1/8" or greater you may have already damaged the chainrings and/or cogs and a new chain may cause skipping or chain suck. In any case, evaluate and change the chain first.

Edit: Oops, I didn't see your last reply. Sounds like you already measured the chain.