I would suggest two sources :
- http://sheldonbrown.com/harris for the Shimano Nexus Dynohub, if you want to buy it alone and build the wheel yourself,
- http://peterwhitecycles.com for all your other needs.

Peter White explains fairly well all generator-based lighting options, their advantages and limitations. I would suggest that you take a good look at that and that you replace the dead generator and headlamp with new stuff from Peter White, as it is much better than the old stuff.

You could also search for a few of my posts with "Schmidt" on this forum. I have one bike with a Nexus dynohub and two with a Schmidt dynohub; all three have a Lumotec headlight and I am really satisfied with the system, as well as with the service I got from Peter White. I use a battery taillight, which avoids lots of wiring on the bike.

The B&M bottle generator he sells is a really cheap way to get good lighting without battery concerns.