Check if new computer account is running XP

I need to check if a new computer account created in AD is running XP -- we do not put SCOM agents on clients. I have created a SCOM 2012 R2 monitor that raises an alert when Security Log Event ID 4741 is detected on a DC. I want Orchestrator to pick up on that alert and then check the OS of the computer account for XP, if true then update the alert that XP exists. A subscription takes care of getting the updated alert to the NOC. I don't use Powershell very often, unfortunately. There are two challenges with this approach, (1) getting the client name out of the 4741 alert description to feed into "computername", and (2) getting a true - false result from Get-ADComputer. I'm completely stuck on (1) and at the following on (2): Get-ADComputer -Filter 'Name -like "computername*"' -Properties OperatingSystem