Change Local Password

I've Googled this and I've gotten tons of good hits.  But here is what our environment looks like.

We have many Windows 2003 x86 & x86 servers.  

We have many Windows 2008 R2 x64 servers.

We have a few Windows 2012 x64 servers.

We need a PowerShell script that will change the Local Admin password on all servers.    We don't need a function, just a script.

We want to be consistent with our scripts so I was told this has to be PowerShell, not a CMD file.