Did you try to use the System Profiles?
Go to the ESM Properties > Profile Management > System Profiles > Add
Profile Type = Data Source
Profile Agent = Windows
Username = domain\user
Password = ****
Event Logs = ?
Interval = ?
The update your datasource to use this profiles by checking the box and selecting it in each datasources
Ah, yes I forgot about that.
It looks like the previous ESM Admin didn't use profiles in this way so it looks like I will have to create a profile and assign it to each data source manually at lease the first time. From then on it will be a simple matter of updating the profile.
Thanks for the quick answer!