Top things to check when assessing network health

I have domain admin access to a new-to-me network which I have been tasked with auditing/assessing with the goal of identifying and prioritizing actions to bring the network up to an acceptable standard.  I'm looking at a fairly high-level audit; something that can be completed within 4-8 hours.

It is a Windows network with Windows 2012, 2008 and 2003 servers serving Windows XP and W7 clients.  There are roughly 120 users and associated PCs.

I'm looking for a guide/cheat-sheet/best practices to help me in performing a fair evaluation of the network.  Below are some of the things I've identified already to give an idea of what I'm looking for.  

-End of life systems (W2003 & XP)
-AD issue - 1/2 the users are members of the Domain Admin group
-AD issues - Password complexity and expiration disabled
-Server hardware with no service agreements
-MS Baseline Security analyzer identified dozens of system behind on Windows patching
-Spiceworks flagged several systems missing anti-virus
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Scott CSenior EngineerCommented:
Take a look at NetworkDetective.

We use this all of the time for network audits of our customer's sites and also potential customers to show where we can make improvements.

The average runtime for a complete network analysis is around 30-60 minutes.

We kick it off, talk to the customers about our company and by the time we're done, we have a slick report and then we can begin discussing how we can help them.

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canuckconsultingAuthor Commented:
I love the look of it but simply don't have the budget.  Or any budget for that matter!
Tim PhillipsWindows Systems AdministratorCommented:
I recommend running an IP scanner and manually going through each IP (not in DHCP scope) to determine its purpose.  It is a great way to find out what is on your network doing what.
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If you have identified "1/2 the users are members of the Domain Admin group", then the domain would normally need to be rebuilt from scratch at once. Security incidents of this severeness are not repairable, the domain cannot be trusted anymore. So I wonder if you really need to do anything with the old domain.
canuckconsultingAuthor Commented:
Can you elaborate on this McKnife?  Why couldn't the users simply be removed from the group.

Thanks for the input Tim.
canuckconsultingAuthor Commented:
I made a mistake in my original post.  It turns out that 1/2 the users are not part of the domain admin group as I said.  Only about ten users are members who should not be.

I'm sorry for my error!
Removing them from the group does not re-establish security. Are you familiar with the term "backdoor"? A domain admin can setup all sorts of invisible backdoors, so if there would have been a user with bad intentions, you are not able to stop him from continuous abuse.
canuckconsultingAuthor Commented:
Thanks guys.
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Network Management

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