Auto Activate and Auto Login using WP MultiSite

I'm looking for a plugin or some code (or advice) on how to do the following:

When a user registers to my network (main site), they fill out the register forms, then get sent to a page that states: "Congratulations! Your site is almost ready ...."

Then they get an email asking them to activate. Then they are sent to an activation page and it states:

"You site is now active. You can visit your site or login"

Then you can click on login, it takes you to the login page and then you fill out the form to login.

Ufff. That's a mouth full!

So, for obvious reasons, I want my users to fill out the registration form, if successful, autologin and redirect to a welcome page.

If that won't work, at least have them autologin after they click on the Activation page.

Any help would be appreciated!

Thanks,
Giovanni