Where can I find a guide to remotely enable WMI access to a Windows client machine

I need to enable the WMI remote access in a lot of client machines in order to connect to these machines and get some information. These machines have installed different versions of windows (Windows XP, Windows 7, Windows Server 2003). I followed the steps described in these articles and it works ok in some cases (the WMI remote access is enabled) but sometimes is just impossible. :(

• Securing a Remote WMI Connection
• Connecting to WMI on a Remote Computer

My question is: Where can I find something like a check list of steps or a step-by-step guide to enable WMI remote access in any Windows machine?

UPDATE

1. Always I use administrator accounts to access the remote machines
2. The most common error which is reported is, Access Denied (decimal -2147024891 or hex 0x80070005). I know which is related to DCOM security settings. so I set the proper remote access to the Administrator accounts in the WMI and DCOM services.
3. I tried disabling the Firewall without luck.

UPDATE 2

I found the solution ¡¡¡, all the client machines which has problems, have the same GPO configuration which makes to the remote logons are being coerced to the guest account, to fix that using the Local Security Policy editor (secpol.msc) you must Select Network access: Sharing and security model for local accounts. and set the value to Classic - local users authenticate as themselves.

Just FYI, you posted the same link twice.

Which machines work, and which don't? Is there a difference depending on the OS?

What error message(s) are you getting?

I would first make sure that the firewall on the remote machine is off, or at least customize the rules in a way that allows RPC traffic. Most new installations of Win7 have the firewall enabled by default, which would block any connections.

Then, make sure that the "Windows Management Instrumentation" service is running, though if that service were stopped now WMI capabilities would be available.

Finally, you need to make sure that you have proper access to the remote computer, but that is something that seems to be explained in the article you mentioned.