Migrate Replication Masters

Hello,
I'm currently building a new SQL 2K8 server that will act as a replication publisher/distributer and will replace an existing one that we have (on a very underpowered box). I've got the all of the subscriptions/publications setup on this new server and I'd now like to point all my production boxes away from the old server to the new server.
Just wondering what the cleanest way of doing this is? Ideally we don't want any downtime and the databases are fairly large so I'm not so sure reinitializaing the subscriptions on these production servers is a very good idea. Is it possible to simply repoint these production servers so instead of pulling subscriptions from the old server they now go to the new server?
Any assistance would be greatly appreciated!