A boot.wim file is the Windows Preinstallation Environment (WinPE). A base.wim file is the main Windows image. (I believe 'base.wim' is what HP generally call their installation WIMs)
Using a WinPE boot CD/USB you can boot into the boot.wim file which will take you into WinPE, from there you can use 'imagex.exe' or 'dism.exe' to apply the base.wim to another disk/computer.
Walkthrough: Create a Custom Windows PE Image: http://technet.microsoft.com/en-us/library/cc709665(v=ws.10).aspx
Apply Images Using DISM: http://technet.microsoft.com/en-us/library/hh824910.aspx