How do i send notifications for private messages and when someone comments on a node a user created?

Hey guys,

I'm working away on a D5 site and one thing I've been avoiding like the plague is figuring out how to set up e-mail notifications.

There are two cases in particular when I'd like to generate an e-mail

1. When someone leaves a comment on a node created by a user, that user needs to get an e-mail with a link to the comment.

2. When someone sends a private message to a user using privatemsg, that user needs to get an e-mail.

For all I know, these are simple to set up. But I see there's a notification module, a workflow module, a simple messaging framework, etc. etc.

What's the easiest, best way to get these two functions going?