Hacker Attempt?

Need to know what is going on here - SBS 2003 box - I found this in my server summary report email this AM.  Is this someone trying to hack into my server?

Source Event ID Last Occurrence Total Occurrences
  Security 529 10/1/2007 4:05 AM 69 *
Logon Failure:
  Reason: Unknown user name or bad password
  User Name: 12345678
  Domain:  
  Logon Type: 3
  Logon Process: Advapi
  Authentication Package: MICROSOFT_AUTHENTICATION_PACKAGE_V1_0
  Workstation Name: MAINSERVER
  Caller User Name: MAINSERVER$
  Caller Domain: DKCONTRACTORS
  Caller Logon ID: (0x0,0x3E7)
  Caller Process ID: 1884
  Transited Services: -
  Source Network Address: -
  Source Port: -
 

Thanks,

Bill