In reply to ClimberEd:
Wash it in whatever you want to, just don't use fabric softener or bleach, the main thing is to make sure it is very well rinsed. Any trace of soap/detergent on the fabric will prevent water beading.
After that if you use re-proofer the choice is between wash in stuff which is easy but coats inside and outside of the garment, or spray on which is more effort but only coats the outside (where you want it).
Then tumble dry on low heat (or iron if you're into such things) to reactivate the DWR and jobs a goodun!