Many people go from OEM licensing to Volume licensing and knowing which machines are on each version (Channel) can be valuable.
Using the below Custom Inventory Rules, you can track if a OS is OEM, Retail, or Volume and get the last 5 of the product key in case you want to match them with keys you may have purchased.
This was written for 5.5 and hasnt been tested for previous versions. As well I havent tested it with windows XP (DIE ALREADY!)
Windows - ShellCommandTextReturn(cmd.exe /c cscript \"C:\windows\system32\slmgr.vbs\" /dli)
Office 2010 - ShellCommandTextReturn(cmd.exe /c cscript \"C:\Program Files\Microsoft Office\Office14\ospp.vbs\" /dstatus)**
Office 2013 - ShellCommandTextReturn(cmd.exe /c cscript \"C:\Program Files (x86)\Microsoft Office\Office15\ospp.vbs\" /dstatus)**
Once you get the info back, use Smart Labels or Reporting to sort through the machines that are Volume/Retail/OEM
** For office you will need to create individual X86/X64 rules pointing to "Program Files" and "program files (X86)"