It is rare that the spokes would be of the right length, plus I wouldn't reccomend re-using the nipples.coalriver-rider said:
In my opinion, if you like the 819's (decent rim btw), just buy the DT hub and a new set of DT spokes sized to fit with that RIM. That way you also have full control over which spokes you would like to use, not just the spokes available in a package.
NS2000X