What kind of chain. I find that in general, modern 8-speed chains with chamfered side plates shift better than the old fashioned 5/6-speed chains. Of course, I'm also running newer ramped freewheels that also contribute to improved shifting, even using a Campy NR derailleur (not known for shifting quality). Also, how do you have your derailleur set up? Chain length can make a big difference in shifting quality since on a NR derailleur it governs how far the jockey wheel is from the freewheel cogs.