This security setting specifies the maximum size of the system event log, which has a theoretical maximum of 4 GB. Practically the limit is lower (~300MB).
Log file sizes must be a multiple of 64 KB. If you enter a value that is not a multiple of 64 KB, Event Viewer will round he log file size up to a multiple of 64 KB.
This setting does not appear in the Local Computer Policy object.
Event Log size and log wrapping should be defined to match the business and security requirements you determined when designing your enterprise security plan. Consider implementing these Event Log settings at the site, domain, or organizational unit level, to take advantage of Group Policy settings.
Computer Configuration\Windows Settings\Security Settings\Event Log
For the Windows Server 2003 family, 16 MB; for Windows XP Professional Service Pack 1, 8 MB; for Windows XP Professional, 512 KB.
Only Windows XP SP2, Windows Server 2003
Event Log security settings are not registry keys.