Is there a windows command that will allow me to verify a domain account/password?
You could use the command RUNAS, it is not technically a commandline to validate credentials, but it CAN be used for that.
runas /noprofile /user:mycomputer\administrator "notepad"
If it fails it returns:
RUNAS ERROR: Unable to run - notepad
1326: Logon failure: unknown user name or bad password.