Parsing XML in Azure Sentinel

CliveWatsonThank you very much with your help on this, your a legend.

Here is the working solution based upon your suggestion

print syslogmsg = '05:19.0Z Some-Server-Name Events - EventFwd [agentInfo@3401 tenantId="0" bpsId="0" tenantGUID="{00000000-0000-0000-0000-000000000000}" tenantNodePath="1\2"] <?xml version="1.0" encoding="utf-8"?><UpdateEvents><MachineInfo><AgentGUID>{00000000-0000-0000-0000-000000000000}</AgentGUID><MachineName>Some-Machine</MachineName><RawMACAddress>112233445566</RawMACAddress><IPAddress>1.1.2.3</IPAddress><AgentVersion>1.2.3.123</AgentVersion><OSName>Windows 41</OSName><TimeZoneBias>-10</TimeZoneBias><UserName>myName</UserName></MachineInfo><BrandCommonUpdater ProductName="Brand Agent" ProductVersion="1.0.0" ProductFamily="AVP"><UpdateEvent><EventID>1234</EventID><Severity>0</Severity><GMTTime>2020-00-00T06:41:02</GMTTime><ProductID>SomeName1999</ProductID><Locale>0001</Locale><Error>0</Error><Type>SomeCore</Type><Version>1234.0</Version><InitiatorID>SOMEAGENT3000</InitiatorID><InitiatorType>OnDemand</InitiatorType><SiteName>Some-Server-Name</SiteName><Description>N/A</Description></UpdateEvent></BrandCommonUpdater></UpdateEvents>'
| parse syslogmsg with * " tenantNodePath" * " " xml 
| extend xml=parse_xml(xml)
| extend MachineName =  xml.UpdateEvents.MachineInfo.MachineName
| extend IPAddress =  xml.UpdateEvents.MachineInfo.IPAddress
| where isnotempty(MachineName)
| project 
    MachineName,
    IPAddress

Edit: Just to clean up the query I have made an adjustment to the solution as suggested by CliveWatson and Ofer