How to reduce Server 2008 R2 x64 winsxs folder

dism /online /cleanup-image /spsuperseded

This freed up about 4GB on the system drive, server was upgraded to SP1 so it removed plenty of pre-SP1 files.

Get remote HP Server serial and product number

Couple of quick powershell commands will get you what you need:

Product number
gwmi win32_ComputerSystem | select OEMStringArray

Serial number
gwmi win32_bios | select SerialNumber