All the new groups are nice, but none really "go" with a classic steel frame. You'll get used to whatever you put on it, so I'd pick a modern group that 1) Performs for the money and 2) Can be repaired, especially the STI's. Shimano is now going to provide parts and support for some 10-sp STI shifters, so picking one of those supported groups may be a good decision in the long run.

With the Euro down, check out Ribbles and PBK, even for Shimano stuff. Great frame, match it up and we'll see you on the road.

There is a thread with "retro bikes with STI/Ergos..." and there are a lot of nice examples there.