PPRuNe Forums - Event ID 529

This message appears in the Security log in the Event Viewer of my XP Home SP3 laptop. It's on a WPA-secured wireless network. The 2nd, 3rd and 4th redacted parts refer to another PC on the network, which runs Vista Home Basic. I presume that something on the Vista PC is attempting to hack into mine - and possibly elsewhere on the web?

Event Type: Failure Audit
Event Source: Security
Event Category: Logon/Logoff
Event ID: 529
Date: 05/09/2009
Time: 20:27:29
User: NT AUTHORITY\SYSTEM
Computer: JM-**********
Description:
Logon Failure:
Reason: Unknown user name or bad password
User Name: ********
Domain: ********-PC
Logon Type: 3
Logon Process: NtLmSsp
Authentication Package: MICROSOFT_AUTHENTICATION_PACKAGE_V1_0
Workstation Name: ********-PC

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The Vista PC has Avast Home Edition, plus Malwarebytes' Anti-Malware and Superantispyware. Should I acquire anything else, to try to track down the miscreant?

(The first step will be updates & scans with the above. I do stress the importance of this to the PC's owner, but it's an uphill struggle!):ugh: