Hi,
P58 is not your bios revision, this is the System model code, eg. all DL360G5's are P58 bios models regardless of actual revision.
Go to the HP site & download the latest online rompaq for the system: http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareIndex.jsp?lang=en&cc=us&prodNameId=3288144&prodTypeId=15351&prodSeriesId=1121486&swLang=8&taskId=135&swEnvOID=4064
The latest revision is 2011.05.02
Hope this helps.
Mark